Drug & supplement interaction

Black Tea + Conjugated Estrogens

Conjugated Estrogens brand names: Premarin, Cenestin, Enjuvia, Premarin Vaginal Cream.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Black Tea has a moderate interaction with Conjugated Estrogens. Theoretically, estrogens might increase the levels and adverse effects of caffeine.

Read the full interaction report
SeverityModerate
LikelihoodProbable
EvidenceB
What do Severity, Likelihood & Evidence mean?
Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Black Tea and Conjugated Estrogens

Here is the interaction we found between these two, with the evidence behind it.

Moderate

ESTROGENS

Why this applies to Conjugated Estrogens

Conjugated Estrogens falls under ESTROGENS — the group Black Tea interacts with.

Theoretically, estrogens might increase the levels and adverse effects of caffeine.
Black tea contains caffeine. Estrogen inhibits caffeine metabolism.
Severity Moderate Likelihood Probable Evidence B

Interaction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the thing to know about pairing your black tea with Premarin (conjugated estrogens): the interaction runs through the caffeine, not the estrogen itself. Estrogen can slow down the liver enzyme that clears caffeine from your body, so the caffeine in your tea tends to hang around longer and build up a bit more than usual.

In plain terms, you may feel the jittery side of caffeine more easily, things like a racing heart, trouble sleeping, restlessness, or feeling wired. The estrogen still works the same way for your menopause symptoms; it's your tolerance for caffeine that shifts. This is rated moderate and likely, though the evidence is modest. If you notice you're more sensitive to caffeine, simply cutting back on tea usually helps. Chat with your pharmacist if it bothers you.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Pollock BG, Wylie M, Stack JA, et al. Inhibition of caffeine metabolism by estrogen replacement therapy in postmenopausal women. J Clin Pharmacol 1999;39:936-40. PubMed

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Black Tea Also Interacts With Other Medications

Black Tea has 8 major, 571 moderate, 114 minor known drug interactions in our database — the Conjugated Estrogens one above is one of them. If you take anything else, check it against the full list below.

Major 8 Moderate 571 Minor 114 No known interaction 2,137 (incl. Conjugated Estrogens)
Taking anything else?

Check Another of Your Medications Against Black Tea

Covers the 2,830 medications we’ve checked against Black Tea. Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With Conjugated Estrogens

This page covers Black Tea only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Conjugated Estrogens page lists 207 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Tiratricol (major) and Acacia Rigidula (moderate).

By severity: 4 major · 172 moderate · 31 minor.

From our pharmacist’s overview on the Conjugated Estrogens page

“Conjugated estrogens (Premarin, Cenestin) are hormone replacement, most often for menopause symptoms, and the 207 supplements here warrant real care before adding any of them. Most of the risk runs through drug processing: 121 entries involve the CYP3A4 enzyme that clears estrogen, which is how St.”

Reviewed by 2 · Jul 18, 2026

Open the Conjugated Estrogens interaction page

One more smart check

Taking Black Tea as Part of a Dietary Supplement Product? Check It for Interactions

We hold 271 real supplement products containing Black Tea, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Black Tea. Your product may carry other ingredients that interact with Conjugated Estrogens too, on top of Black Tea — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Black Tea and Conjugated Estrogens Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Black Tea
Top 25%

#280 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Conjugated Estrogens
Steady interest

#1,486 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Black Tea

What is Black Tea?

  • Mental alertness and energy
  • Heart health support
  • Blood pressure and cholesterol
  • Digestive complaints
  • Weight management
  • Antioxidant support

Black tea is a popular caffeinated drink made from the fully oxidized leaves of the Camellia sinensis plant, and it contains caffeine and antioxidant plant compounds. Moderate tea drinking is generally safe for most adults and may modestly support heart health and alertness, but it is not a proven treatment for any disease. If you are pregnant, breastfeeding, sensitive to caffeine, or taking medicines, talk to your pharmacist or doctor.

Read the full Black Tea monograph & all interactions
Keep checking

Other Drugs & Black Tea

Browse every other medication we’ve checked against Black Tea — both the ones with a known interaction and the ones without. Select any drug for the full detail.

8Major
571Moderate
114Minor
2,136No known interaction
8 Major 571 Moderate 114 Minor 2,136 No interaction
Major

8 interactions

Moderate

571 interactions

Showing 60 of 571 moderate interactions — see all 571 on the Black Tea page.

Minor

114 interactions

Showing 60 of 114 minor interactions — see all 114 on the Black Tea page.

No interaction 2,136 drugs checked — show the list

We also checked Black Tea against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,136 medications checked with no known interaction — see the full Black Tea list.

See the full Black Tea interactions page
See every supplement checked against Conjugated Estrogens, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Black Tea monograph › Uses, safety, and every drug interaction in one place Conjugated Estrogens supplement interactions › Every supplement checked against Conjugated Estrogens, ranked by severity Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Black Tea and Conjugated Estrogens Together: Common Questions

Can you take Black Tea with Conjugated Estrogens?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Black Tea and Conjugated Estrogens interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Conjugated Estrogens and Black Tea?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.