Meta Information
ID:estradiol-topical
Name:Estradiol
Schema Version:2.4_uniform_evidence_2026_06_18
Created
2026-05-21T22:30:00Z
Model
phase-a-upgrade-claude-sonnet-4.6
Interactions
Target id:
/class/aromatase-inhibitors
Target name:
Aromatase Inhibitors
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Aromatase inhibitors are used to lower estrogen levels, often for treating hormone-sensitive cancers. Applying exogenous estradiol directly counteracts their therapeutic purpose.
Actionable advice:
Estradiol should not be used at all while on aromatase inhibitor therapy.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
It contains two female hormones, an estrogen called ethinyl estradiol, and a progestin called norelgestromin.
Label source:
Action type:
avoid
Target id:
/class/serms
Target name:
Selective Estrogen Receptor Modulators (SERMs)
Severity:
major
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
SERMs like tamoxifen and raloxifene work by blocking or activating estrogen receptors in different tissues. Co-administration with estradiol can lead to unpredictable effects and interfere with the intended action of the SERM.
Actionable advice:
Estradiol should not be used with SERMs unless specifically directed by an oncologist or specialist.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
The underlying mechanism is unknown, but may be related to the estrogen-like effect of tamoxifen.
Label source:
Action type:
avoid
Target id:
/condition/estrogen-dependent-cancer
Target name:
History of Estrogen-Dependent Cancer
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Estradiol can stimulate the growth of hormone-sensitive cancers, such as certain types of breast or endometrial cancer. Its use is contraindicated in individuals with a known or suspected history of these conditions.
Actionable advice:
This should not be used with a personal history of breast cancer or other estrogen-dependent tumors.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Your healthcare provider should check any unusual vaginal bleeding to find out the cause. currently have or have had certain cancers Estrogens may increase the chance of getting certain types of cancers, including cancer of the breast or uterus.
Label source:
Action type:
avoid
Target id:
/condition/history-of-vte
Target name:
History of Blood Clots (VTE/DVT/PE)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Systemic estrogens are known to increase the risk of blood clots. While the risk from low-dose topical application is very low, it is generally contraindicated in individuals with an active or past history of venous thromboembolism.
Actionable advice:
This should not be used with a history of deep vein thrombosis or pulmonary embolism.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Norelgestromin and ethinyl estradiol transdermal system may increase your risk of blood clots after surgery.
Label source:
Action type:
avoid
Target id:
/condition/pregnancy
Target name:
Pregnancy
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Estrogens are contraindicated during pregnancy due to potential harm to the developing fetus.
Actionable advice:
This should not be used during pregnancy or when planning to become pregnant.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
There are no data with the use of LYLLANA in pregnant women; however, epidemiologic studies and meta-analyses have not found an increased risk of genital or nongenital birth defects (including cardiac anomalies and limb-reduction defects) following exposure to combined hormonal contraceptives (estrogens and progestins) before conception or during early pregnancy.
Label source:
Action type:
avoid
Target id:
/condition/hepatic-impairment
Target name:
Severe Liver Disease
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
The liver is responsible for metabolizing estrogens. In severe liver disease, estradiol levels can build up, increasing the risk of side effects.
Actionable advice:
Use should be avoided with severe liver impairment.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
5.10 Hepatic Impairment and/or Past History of Cholestatic Jaundice Estrogens may be poorly metabolized in women with hepatic impairment.
Label source:
Action type:
avoid
Target id:
/condition/undiagnosed-vaginal-bleeding
Target name:
Undiagnosed Abnormal Vaginal Bleeding
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Abnormal vaginal bleeding must be investigated before starting estrogen therapy to rule out underlying conditions like endometrial cancer, which could be worsened by estrogen.
Actionable advice:
Topical/vaginal estradiol should not be started until any unexplained vaginal bleeding has been evaluated by a doctor; estrogen can mask or worsen a serious underlying cause.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
● have unexplained vaginal bleeding ● are pregnant or think you may be pregnant.
Label source:
Action type:
avoid
Target id:
/class/broad-spectrum-inducers
Target name:
Strong Metabolic Enzyme Inducers (e.g., Rifampin, some anticonvulsants)
Severity:
moderate
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
These drugs speed up the liver's metabolism of any systemically absorbed estradiol, which can lower its concentration in the blood and reduce its effectiveness.
Actionable advice:
It is worth being aware that the effectiveness of estradiol may be reduced; it is a good idea to consult a doctor about potential dose adjustments.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
John's wort ( Hypericum perforatum ) preparations, phenobarbital, carbamazepine and rifampin may reduce plasma concentrations of estrogens, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile.
Label source:
Action type:
adjust_with_prescriber
Target id:
/intervention/saint-johns-wort
Target name:
Saint John's Wort
Severity:
moderate
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
St. John's Wort is a potent inducer of the CYP3A4 enzyme, which breaks down estradiol. This can significantly decrease the levels and effectiveness of any absorbed estradiol.
Actionable advice:
St. John's Wort is best avoided while using estradiol products.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
CONCLUSION: St John's wort causes an induction of ethinyl estradiol-norethindrone metabolism consistent with increased CYP3A activity.
Label source:
PubMed: The interaction between St John's wort and an oral contraceptive. (PMID 14663455)
Action type:
avoid
Target id:
/class/cyp3a4-strong-inhibitors
Target name:
Strong CYP3A4 Inhibitors (e.g., Ketoconazole, Clarithromycin)
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
These drugs block the CYP3A4 enzyme, slowing the breakdown of any absorbed estradiol. This can lead to higher-than-expected estrogen levels and an increased risk of side effects.
Actionable advice:
This is best used with caution, and it is a good idea to monitor for estrogen-related side effects like breast tenderness or nausea.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Inhibitors of CYP3A4 such as erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, and grapefruit juice may increase plasma concentrations of estrogens and may result in adverse reactions.
Label source:
Action type:
monitor
Target id:
/intervention/lamotrigine
Target name:
Lamotrigine
Severity:
moderate
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Systemic estrogens are known to significantly increase the clearance of lamotrigine, reducing its blood levels and potentially leading to a loss of seizure control or mood stabilization.
Actionable advice:
If you take lamotrigine, discuss this with your doctor as your lamotrigine dose may need adjustment.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Some medicines and grapefruit juice may increase your level of the hormone ethinyl estradiol if used together, including: ● acetaminophen ● ascorbic acid ● medicines that affect how your liver breaks down other medicines (itraconazole, ketoconazole, voriconazole, and fluconazole) ● certain HIV medicines (atazanavir, indinavir) ● atorvastatin ● rosuvastatin ● etravirine Hormonal birth control methods may interact with lamotrigine, an anti-seizure medicine used for epilepsy.
Label source:
Action type:
adjust_with_prescriber
Target id:
/condition/compromised-skin-barrier
Target name:
Broken, Irritated, or Sunburned Skin
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Applying estradiol to skin that is not intact (e.g., cuts, eczema, sunburn) can significantly increase the amount of drug absorbed into the bloodstream, raising the risk of systemic side effects.
Actionable advice:
This is best not applied to broken or irritated skin; it is best to wait until the skin has fully healed.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
12.3 Pharmacokinetics Absorption Estradiol diffuses across intact skin and into the systemic circulation by a passive absorption process, with diffusion across the stratum corneum being the rate-limiting factor.
Label source:
Action type:
informational_none
Target id:
/dietary/grapefruit-pomelo
Target name:
Grapefruit and Grapefruit Juice
Severity:
minor
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Grapefruit inhibits the CYP3A4 enzyme, which can slow the metabolism of systemically absorbed estradiol, potentially increasing its levels and side effects. The effect is less pronounced than with oral drugs.
Actionable advice:
It is prudent to limit or avoid grapefruit consumption while using this medication.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Inhibitors of CYP3A4 such as erythromycin, clarithromycin, ketoconazole, itraconazole, ritonavir, and grapefruit juice may increase plasma concentrations of estrogens and may result in adverse reactions.
Label source:
Action type:
avoid
Target id:
/class/thyroid-hormones
Target name:
Thyroid Hormones (e.g., Levothyroxine)
Severity:
minor
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Systemically absorbed estrogen can increase levels of thyroid-binding globulin (TBG), which binds to thyroid hormone. This may increase the required dose of thyroid hormone replacement in individuals with hypothyroidism.
Actionable advice:
If you take thyroid medication, your doctor may need to monitor your thyroid function tests after starting estradiol.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Women dependent on thyroid hormone replacement therapy who are also receiving estrogens may require increased doses of their thyroid replacement therapy.
Label source:
Action type:
separate
Target id:
/biomarker/thyroid-panel
Target name:
Thyroid Function Tests
Severity:
minor
Interaction type:
assay_interference
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Absorbed estrogen increases thyroid-binding globulin (TBG), which can falsely elevate total T4 and T3 levels. Free T4 and TSH levels are typically the most reliable indicators of thyroid status in this context.
Actionable advice:
It is generally best to let the person interpreting lab results know about the use of an estradiol product.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Monitor thyroid function in these women during treatment with LYLLANA to maintain their free thyroid hormone levels in an acceptable range.
Label source:
Action type:
monitor
Target id:
/biomarker/comprehensive-sex-hormone-panel
Target name:
Sex Hormone Panel
Severity:
minor
Interaction type:
assay_interference
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Absorbed estrogen increases sex hormone-binding globulin (SHBG), which can elevate total testosterone and estradiol levels. Free hormone levels may be more clinically relevant.
Actionable advice:
It is generally best for a doctor to be aware of topical estradiol use when interpreting hormone panels.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Other binding proteins may be elevated in serum, for example, corticosteroid-binding globulin (CBG), sex hormone-binding globulin (SHBG), leading to increased total circulating corticosteroids and sex steroids, respectively.
Label source:
Action type:
monitor
Target id:
/class/corticosteroids
Target name:
Corticosteroids (e.g., Prednisone)
Severity:
minor
Interaction type:
synergistic
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Estrogens may decrease the clearance of corticosteroids, potentially enhancing their effects and side effects. This is more relevant with higher systemic absorption.
Actionable advice:
It is worth watching out for increased corticosteroid effects if both medications are used concurrently.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Reference ID: 3165107 7.9 Cholestyramine
Cholestyramine may increase the clearance of corticosteroids.
Label source:
Action type:
monitor
Target id:
/lifestyle/tobacco-smoking
Target name:
Tobacco Smoking
Severity:
minor
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Smoking induces liver enzymes (primarily CYP1A2) that metabolize estradiol, which can lead to lower estrogen levels and potentially reduced efficacy of the treatment.
Actionable advice:
Smoking may reduce the effectiveness of estradiol therapy.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
The parameters of CSE production were optimized for a 2.5-min cigarette burning and a cell culture medium as CSE solvent. A reliable, concentration-dependent induction of CYP1A1 and CYP1A2 by CSE across different donors and cigarettes was verified based on an enzyme activity (LC-MS/MS) and mRNA expression levels (qRT-PCR).
Label source:
Action type:
informational_none
Target id:
/class/anticoagulants-antiplatelets
Target name:
Anticoagulants and Antiplatelets
Severity:
minor
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Systemic estrogens can affect blood clotting factors, but the risk with low-dose topical estradiol is considered minimal. However, a theoretical interaction exists, and caution is advised.
Actionable advice:
It is generally best to let a doctor know about topical estradiol use if blood-thinning medications are taken.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
If unscheduled bleeding persists longer than a few cycles, consider causes other than norelgestromin and ethinyl estradiol transdermal system.
Label source:
Action type:
informational_none
Target id:
/class/topical-medications-general
Target name:
Other Topical Creams or Ointments
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
1
Hours after target:
1
Description:
Applying other topical products to the same area can interfere with the absorption of estradiol or dilute the medication, potentially reducing its effectiveness.
Actionable advice:
Other products on the same skin area are best applied at least 1 hour before or after estradiol.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Occlusion of the area where the topical drug product is applied with clothing or other barriers is not recommended until estradiol gel 0.1% has completely dried.
Label source:
Action type:
separate
Target id:
/condition/hormone-sensitive-cancer
Target name:
History of Hormone-Sensitive Cancer (Breast, Ovarian, Uterine)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Any systemic absorption of estradiol, even from topical application, could potentially stimulate the growth of hormone-receptor-positive cancer cells.
Actionable advice:
This should be strictly avoided with a personal history of estrogen-sensitive cancers.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
These include an increased risk of breast cancer.
Label source:
Action type:
avoid
Target id:
/condition/lactation
Target name:
Breastfeeding (Lactation)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
It is unknown if topically applied estradiol is excreted in breast milk, but it is best to avoid it to prevent potential hormonal effects on the infant.
Actionable advice:
It should be avoided completely while breastfeeding.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
A small amount of hormones from the norelgestromin and ethinyl estradiol transdermal system patch may pass into your breast milk.
Label source:
Action type:
avoid
Target id:
/intervention/sunscreen
Target name:
Broad-Spectrum Sunscreen (SPF)
Severity:
major
Interaction type:
synergistic
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Sun exposure degrades collagen and counteracts the benefits of any anti-aging topical, including estradiol. Sunscreen is essential to protect the skin and allow estradiol to work effectively.
Actionable advice:
Broad-spectrum sunscreen should be applied every morning as the final step in a skincare routine.
Validation status:
validated_via_expert_review
Evidence tier:
tier_c
Evidence basis:
expert_review_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Most signs of premature skin aging are caused by sun exposure.
Label source:
Clinical guidance: American Academy of Dermatology — premature skin aging
Action type:
informational_none
Target id:
/procedure/skin-resurfacing
Target name:
Ablative Skin Procedures (Laser, Deep Peels, Microneedling)
Severity:
moderate
Interaction type:
adverse
Nature:
temporal
Temporal spacing:
Hours before target:
72
Hours after target:
168
Description:
Applying estradiol to skin with a compromised barrier after procedures like laser resurfacing or chemical peels can cause significant irritation and unpredictable systemic absorption.
Actionable advice:
Use should be discontinued for at least 3 days before and until the skin is fully healed after such procedures.
Validation status:
validated_via_expert_review
Evidence tier:
tier_c
Evidence basis:
expert_review_verbatim
Evidence anchors:
Exact phrase from label:
Applying topical agents to skin with an impaired epidermal barrier after laser resurfacing or chemical peels increases absorption and irritation; standard post-procedure dermatologic guidance is to withhold actives until re-epithelialization is complete.
Label source:
Expert review: standard dermatologic post-procedure care (AAD/ASDS) — withhold active topicals (retinoids, AHAs, hormones) until barrier restoration after ablative procedures
Action type:
avoid
Target id:
/condition/close-physical-contact
Target name:
Close Physical Contact with Others (Partners, Children)
Severity:
moderate
Interaction type:
adverse
Nature:
temporal
Temporal spacing:
Hours before target:
null
Hours after target:
1
Description:
The cream can transfer to others through direct skin contact, potentially causing unintended hormonal exposure, especially to men and children.
Actionable advice:
Prolonged contact of the treated skin with others is best avoided for at least one hour after application.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Exact phrase from label:
There is a potential for drug transfer from one individual to the other following physical contact of Divigel application sites.
Label source:
FDA label: Divigel (estradiol gel) — Section 5.20 Potential for Estradiol Transfer
Action type:
separate
Target id:
/biomarker/estradiol
Target name:
Estradiol Blood Test
Severity:
moderate
Interaction type:
assay_interference
Nature:
temporal
Temporal spacing:
Hours before target:
24
Hours after target:
null
Description:
Systemic absorption from topical application, although typically low, can affect serum estradiol measurements, leading to a potentially inaccurate reading of your endogenous hormone levels.
Actionable advice:
Skip application for 24 hours before having your blood drawn for hormone testing.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Absorption of NGMN and EE following application of norelgestromin and ethinyl estradiol transdermal system to the buttock, upper outer arm, abdomen and upper torso (excluding breast) was examined.
Label source:
Action type:
separate
Target id:
/intervention/tretinoin
Target name:
Tretinoin (Topical)
Severity:
minor
Interaction type:
synergistic
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Both topical estradiol and tretinoin stimulate collagen production in the skin, potentially leading to enhanced anti-aging effects when used together.
Actionable advice:
Can be used in the same skincare routine, often at different times (e.g., estradiol AM, tretinoin PM) to minimize irritation.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
topical estrogen
Label source:
Primary literature: Verdier-Sevrain S, Climacteric 2007 — Effect of estrogens on skin (collagen, hydration; complementary to topical retinoid mechanism)
Action type:
informational_none
Target id:
/class/exfoliating-acids
Target name:
Exfoliating Acids (AHAs, BHAs)
Severity:
minor
Interaction type:
adverse
Nature:
temporal
Temporal spacing:
Hours before target:
0.5
Hours after target:
0.5
Description:
Applying potent exfoliants like AHAs or BHAs at the same time as estradiol may increase the risk of skin irritation, redness, or sensitivity.
Actionable advice:
Estradiol and exfoliating acids are best applied at different times of the day (e.g., one in the morning, one at night).
Validation status:
validated_via_expert_review
Evidence tier:
tier_c
Evidence basis:
expert_review_verbatim
Evidence anchors:
Exact phrase from label:
Co-application of potent exfoliating acids (AHAs/BHAs) with other actives at the same time increases stratum corneum disruption and irritation; standard dermatologic guidance is to alternate timing (AM/PM) to maintain barrier integrity.
Label source:
Expert review: standard dermatologic layering guidance (AAD) — alternate timing for exfoliating acids and other actives
Action type:
informational_none
Target id:
/class/photosensitizing-agents
Target name:
Photosensitizing Agents
Severity:
minor
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Concurrent use with other topical or systemic agents that increase sun sensitivity can heighten the risk of sun damage, working against the goals of facial healthspan.
Actionable advice:
Extra diligence with sun protection may help when using other photosensitizing products or medications.
Validation status:
validated_via_expert_review
Evidence tier:
tier_c
Evidence basis:
expert_review_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Concurrent use of multiple photosensitizing agents (topical retinoids, AHAs, certain systemic medications) increases cumulative photosensitivity risk; comprehensive sun protection is required.
Label source:
Expert review: standard dermatologic photosensitivity guidance (AAD)
Action type:
informational_none
Target id:
/intervention/levothyroxine
Target name:
Levothyroxine (Thyroid Hormone)
Severity:
minor
Interaction type:
assay_interference
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Systemic estrogen can increase levels of thyroid-binding globulin (TBG), potentially lowering free thyroid hormone levels. This is a very low risk with topical facial use.
Actionable advice:
If you are on thyroid medication, be aware of this theoretical interaction and monitor thyroid function as usual.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Inform patients that agents such as iron and calcium supplements and antacids can decrease the absorption of levothyroxine.
Label source:
FDA label: Levothyroxine (Synthroid)
Action type:
monitor
Target id:
/biomarker/shbg
Target name:
Sex Hormone Binding Globulin (SHBG)
Severity:
minor
Interaction type:
assay_interference
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Any systemically absorbed estradiol can increase liver production of SHBG, which binds to sex hormones. This is a physiological effect, not just an assay interference.
Actionable advice:
Long-term use might slightly elevate SHBG levels, a factor worth considering when interpreting hormone panels.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Percent change in SHBG concentrations was higher for norelgestromin and ethinyl estradiol transdermal system users compared to women taking the oral contraceptive; percent change in CBG concentrations was similar for norelgestromin and ethinyl estradiol transdermal system and oral contraceptive users.
Label source:
Action type:
monitor
Target id:
/circadian/sleep
Target name:
Bedtime Routine
Severity:
minor
Interaction type:
synergistic
Nature:
temporal
Temporal spacing:
Hours before target:
1
Hours after target:
0
Description:
Applying estradiol at night allows it to work uninterrupted on clean skin, aligning with the body's natural overnight repair cycles and avoiding daytime sun exposure.
Actionable advice:
It is best applied to a clean face as part of a nighttime skincare routine.
Validation status:
validated_via_expert_review
Evidence tier:
tier_c
Evidence basis:
expert_review_verbatim
Evidence anchors:
Exact phrase from label:
Nighttime application of topical agents to clean skin aligns with the body's overnight skin repair processes and avoids interference from daytime exposures (sunscreen, makeup, sweat).
Label source:
Expert review: standard dermatologic skincare-timing guidance (AAD)
Action type:
informational_none
Derived From
estradiol_topical_disease
Provenance Note
Interactions duplicated from 'estradiol_topical_disease'. Topical estradiol; same local interactions.
Merged From
- estradiol_facial_healthspan