Meta Information
ID:menopausal-hrt
Name:
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/broad-spectrum-inducers
Target name:
Broad-Spectrum Metabolic Enzyme Inducers
Severity:
major
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Certain medications (like some anticonvulsants and antibiotics like rifampin) strongly increase the activity of liver enzymes (CYP3A4) that break down estrogens and progestins, significantly lowering HRT levels and reducing its effectiveness.
Actionable advice:
This combination should be avoided; if necessary, the HRT dose may need to be significantly increased and monitored.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Inducers of CYP3A4 such as St. John's wort (Hypericum perforatum) preparations, phenobarbital, carbamazepine, and rifampin may reduce plasma concentrations of estrogens and progestins, possibly resulting in a decrease in therapeutic effects and/or changes in the uterine bleeding profile.
Label source:
FDA label: Estradiol/Progesterone (Prempro/Bijuva)
Action type:
avoid
Target id:
/intervention/saint-johns-wort
Target name:
Saint John's Wort
Severity:
major
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 metabolizes the hormones in HRT, leading to lower hormone levels and potential loss of symptom control.
Actionable advice:
St. John's Wort should be avoided while on menopausal HRT.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Since then, subsequent research has shown that SJW altered the pharmacokinetics of drugs such as digoxin, tacrolimus, indinavir, warfarin, alprazolam, simvastatin, or oral contraceptives. These interactions were caused by pregnane-X-receptor (PXR) activation. Preparations of SJW are potent activators of PXR and hence inducers of cytochrome P450 enzymes (most importantly CYP3A4) and P-glycoprotein.
Label source:
PubMed: Clinical relevance of St. John's wort drug interactions revisited. (PMID 31742659)
Action type:
avoid
Target id:
/class/cyp3a4-strong-inhibitors
Target name:
Strong CYP3A4 Inhibitors
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Strong inhibitors of the CYP3A4 enzyme (e.g., ketoconazole, clarithromycin, ritonavir) block the breakdown of HRT hormones, leading to elevated levels and an increased risk of side effects like blood clots and breast tenderness.
Actionable advice:
This combination should be avoided; if unavoidable, a lower dose of HRT and close monitoring are required.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
In-vitro and in-vivo studies have shown that estrogens and progestins are metabolized partially by cytochrome P450 3A4 (CYP3A4). Therefore, inducers or inhibitors of CYP3A4 may affect estrogen and progestin drug metabolism.
Label source:
FDA label: Estradiol/Progesterone (Prempro/Bijuva)
Action type:
avoid
Target id:
/dietary/grapefruit-pomelo
Target name:
Grapefruit and Grapefruit Juice
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Grapefruit contains compounds that inhibit the CYP3A4 enzyme in the gut and liver, which can increase the absorption and levels of oral estrogens, raising the risk of side effects.
Actionable advice:
Regular consumption of grapefruit or grapefruit juice is best avoided when taking oral HRT.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
These flavonoids interact with the metabolism of drugs such as 17 beta-estradiol and other steroids that are extensively metabolised through the P-450NF (P-450 IIIA4) enzyme or closely related P-450 systems.
Label source:
PubMed: Maturitas (1994)
Source url:
Exact phrase from label:
This study demonstrates that grapefruit juice may alter the metabolic degradation of estrogens, and increase the bioavailable amounts of 17 beta-estradiol and its metabolite estrone, presumably by affecting the oxidative degradation of estrogens.
Label source:
PubMed: Maturitas (1994)
Source url:
Exact phrase from label:
The consistent findings across studies of diverse cytochrome P450 (CYP) 3A substrates support the mechanistic hypothesis that 1 or more grapefruit juice components inhibit CYP3A enzymes in the gastrointestinal tract.
Label source:
PubMed: Clinical pharmacokinetics (1997)
Action type:
avoid
Target id:
/intervention/levothyroxine
Target name:
Levothyroxine
Severity:
moderate
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Oral estrogens increase levels of thyroid-binding globulin (TBG), a protein that binds to thyroid hormone, which can decrease the amount of free, active thyroid hormone available. This interaction is less significant with transdermal HRT.
Actionable advice:
If you take thyroid medication, your dose may need to be adjusted after starting oral HRT; regular thyroid function monitoring is essential.
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:
separate
Target id:
/intervention/lamotrigine
Target name:
Lamotrigine
Severity:
major
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Oral estrogen-containing HRT can significantly increase the clearance of lamotrigine, substantially lowering its blood levels and potentially leading to a loss of seizure control or mood stabilization.
Actionable advice:
Oral HRT should not be combined with lamotrigine; if necessary, significant lamotrigine dose adjustments and close monitoring can be expected.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
OCs can also decrease the concentrations of AEDs such as lamotrigine and, thereby, increase the risk of seizures.
Label source:
Reddy (2010), PMC2848501. Supports estrogen inducing lamotrigine glucuronidation -> lower levels -> seizure risk. FLAG: the evidence is for oral CONTRACEPTIVES (higher-potency ethinylestradiol); the same mechanism applies to menopausal HRT but with smaller magnitude.
Action type:
avoid
Target id:
/condition/history-hormone-sensitive-cancer
Target name:
History of Breast or Endometrial Cancer
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Menopausal HRT is contraindicated in individuals with a current or past history of estrogen-sensitive cancers, as it may promote cancer recurrence or growth.
Actionable advice:
Menopausal HRT should not be used with a history of breast, uterine, or other hormone-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:
Breast cancer or a history of breast cancer [see Warnings and Precautions (5.2) ]. Estrogen-dependent neoplasia [see Warnings and Precautions (5.2) ].
Label source:
FDA label: Estradiol/Progesterone (Prempro/Bijuva)
Action type:
avoid
Target id:
/condition/active-vte
Target name:
Active or History of VTE/DVT/PE
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Estrogen increases the risk of venous thromboembolism (VTE), including deep vein thrombosis (DVT) and pulmonary embolism (PE). It is contraindicated in those with an active clot or a high-risk history.
Actionable advice:
Menopausal HRT should not be used with a current blood clot or a history of clots related to estrogen use.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Manage risk factors for arterial vascular disease and/or venous thromboembolisum. Discontinue if an arterial or venous thrombotic or thromboembolic event occurs.
Label source:
FDA label: Estradiol/Progesterone (Prempro/Bijuva)
Action type:
avoid
Target id:
/condition/smoking
Target name:
Smoking
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Smoking significantly amplifies the risk of serious cardiovascular events, such as blood clots, heart attack, and stroke, when combined with systemic HRT, particularly in women over 35.
Actionable advice:
It is strongly recommended to stop smoking before starting and while using menopausal HRT.
Validation status:
validated_via_class_inference
Evidence tier:
tier_c
Evidence basis:
class_inference_summary
Evidence anchors:
Source url:
Established mechanism / class pharmacology (no single primary source quoted)
Exact phrase from label:
Mechanistic inference: smoking increases the cardiovascular and thromboembolic (VTE, stroke, MI) risk of systemic estrogen therapy; estrogen product labeling carries cardiovascular-risk warnings and the smoking-plus-estrogen risk is well established. Strongly grounded clinically; rendered as class inference rather than one verbatim label quote.
Label source:
Class inference
Action type:
informational_none
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 the primary site of hormone metabolism. In cases of severe liver dysfunction, hormone clearance is impaired, leading to accumulation and increased risk, making HRT contraindicated.
Actionable advice:
Menopausal HRT should not be used in active or severe liver disease.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Hepatic impairment or disease [see Warnings and Precautions (5.
Label source:
FDA label: Estradiol/Progesterone (Prempro)
Action type:
avoid
Target id:
/condition/unexplained-vaginal-bleeding
Target name:
Unexplained Vaginal Bleeding
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Unexplained vaginal bleeding must be diagnosed before starting HRT, as it could be a sign of an underlying condition, such as endometrial hyperplasia or cancer, which would be worsened by HRT.
Actionable advice:
Any abnormal vaginal bleeding should be fully investigated by a doctor before HRT is considered.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Abnormal genital bleeding of unknown etiology [see Warnings and Precautions (5.2) ].
Label source:
FDA label: Estradiol/Progesterone (Prempro/Bijuva)
Action type:
informational_none
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:
Menopausal HRT is not a form of contraception and is contraindicated during pregnancy due to potential harm to the developing fetus.
Actionable advice:
Menopausal HRT should not be used during pregnancy or possible pregnancy.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
BIJUVA is not indicated for use in pregnancy. There are no data with the use of BIJUVA in pregnant women,
Label source:
FDA label: Estradiol/Progesterone (Prempro/Bijuva)
Action type:
avoid
Target id:
/class/bile-acid-sequestrants
Target name:
Bile Acid Sequestrants
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
Bile acid sequestrants (e.g., cholestyramine) can bind to oral estrogens in the intestine, preventing their absorption and reducing the effectiveness of HRT.
Actionable advice:
Oral HRT is best taken at least 4 hours before or 4 hours after a bile acid sequestrant.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Because cholestyramine binds bile acids, QUESTRAN may interfere with normal fat digestion
and absorption and thus may prevent absorption of fat-soluble vitamins such as A, D, E and
K.
Label source:
Action type:
separate
Target id:
/class/aromatase-inhibitors
Target name:
Aromatase Inhibitors
Severity:
major
Interaction type:
diminishing
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Aromatase inhibitors (e.g., anastrozole, letrozole) work by blocking estrogen production and are used to treat hormone-sensitive breast cancer. Taking estrogen-containing HRT directly counteracts their therapeutic purpose.
Actionable advice:
Menopausal HRT should not be taken concurrently with aromatase inhibitors.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
12 CLINICAL PHARMACOLOGY
12.1 Mechanism of Action
The growth of many cancers of the breast is stimulated or maintained by estrogens.
Label source:
Action type:
avoid
Target id:
/class/serms
Target name:
Selective Estrogen Receptor Modulators (SERMs)
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
SERMs (e.g., tamoxifen, raloxifene) and estrogens compete for the same receptors. Using them together can lead to unpredictable effects and is not recommended.
Actionable advice:
Menopausal HRT should not be used at the same time as a SERM.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
In this rat model, tamoxifen appears to exert its antitumor effects by binding the estrogen receptors.
Label source:
Action type:
avoid
Target id:
/class/corticosteroids
Target name:
Corticosteroids
Severity:
minor
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Estrogens can inhibit the metabolism of corticosteroids, potentially increasing their levels and effects, which may require a dose adjustment of the corticosteroid.
Actionable advice:
The corticosteroid dose may need to be lowered; watching for increased side effects may help.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
7.12 Estrogens, Including Oral Contraceptives
Estrogens may decrease the hepatic metabolism of certain corticosteroids, thereby increasing their effect.
Label source:
Action type:
adjust_with_prescriber
Target id:
/biomarker/thyroid-panel
Target name:
Thyroid Panel
Severity:
moderate
Interaction type:
assay_interference
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Oral estrogen increases thyroid-binding globulin (TBG), which can lead to an artificially high Total T4 and Total T3 reading. Free T4 and TSH levels are more reliable indicators of thyroid status.
Actionable advice:
It is a good idea to let a doctor know about oral HRT use when interpreting thyroid tests, relying on Free T4 and TSH for accuracy.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Estrogen administration leads to increased thyroid-binding globulin (TBG) levels. Women with normal thyroid function can compensate for the increased TBG by making more thyroid hormone, thus maintaining free T4 and T3 serum concentrations in the normal range.
Label source:
FDA label: Estradiol/Progesterone (Prempro/Bijuva)
Action type:
monitor
Target id:
/biomarker/lipid-panel
Target name:
Lipid Panel
Severity:
minor
Interaction type:
assay_interference
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
HRT can alter lipid profiles, typically by lowering LDL ('bad') cholesterol and raising HDL ('good') cholesterol, but oral estrogens may also increase triglycerides.
Actionable advice:
HRT will affect lipid panel results; monitoring triglycerides is worthwhile, especially with oral formulations.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Source url:
Exact phrase from label:
Increased plasma high-density lipoprotein (HDL) and HDL2 cholesterol subfraction concentrations, reduced low-density lipoprotein (LDL) cholesterol concentrations, increased triglyceride levels.
Label source:
FDA label: Estradiol/Progesterone (Prempro/Bijuva)
Action type:
monitor
Target id:
/procedure/topical-application-site-rotation
Target name:
Transdermal HRT Application Site Rotation
Severity:
moderate
Interaction type:
requirement
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Consistent application of transdermal HRT (patches, gels) to the same area of skin can cause irritation and may lead to inconsistent hormone absorption over time.
Actionable advice:
Rotate the application site for transdermal HRT with each new dose as instructed by the product labeling.
Validation status:
validated_via_class_inference
Evidence tier:
tier_c
Evidence basis:
class_inference_summary
Evidence anchors:
Source url:
Established mechanism / class pharmacology (no single primary source quoted)
Exact phrase from label:
Practical administration guidance: for transdermal estradiol, rotating application sites reduces local skin irritation and follows standard patch/gel directions. Not a pharmacologic interaction.
Label source:
Class inference
Action type:
informational_none
Target id:
/intervention/sunscreen
Target name:
Sunscreen and Other Lotions
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
1
Hours after target:
1
Description:
Applying sunscreen or other lotions to the skin shortly before or after applying transdermal HRT gel can interfere with its absorption through the skin.
Actionable advice:
Sunscreen or lotion is best applied to the same area at least one hour after HRT gel.
Validation status:
validated_via_class_inference
Evidence tier:
tier_c
Evidence basis:
class_inference_summary
Evidence anchors:
Source url:
Established mechanism / class pharmacology (no single primary source quoted)
Exact phrase from label:
Pharmaceutical inference: topical products (including sunscreen) on the same skin area as a transdermal estradiol gel/patch can alter local absorption; separate application. Practical, formulation-level caution.
Label source:
Class inference
Action type:
separate