Drug & supplement interaction

Blessed Thistle + Famotidine

Famotidine brand names: Pepcid, Famotidine, Pepcid AC, Famotidine Injection.

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

Blessed Thistle has a minor interaction with Famotidine. Theoretically, blessed thistle might decrease the effectiveness of H2-blockers.

Read the full interaction report
SeverityMinor
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Blessed Thistle and Famotidine

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

Minor

H2-BLOCKERS

Why this applies to Famotidine

Famotidine falls under H2-BLOCKERS — the group Blessed Thistle interacts with.

Theoretically, blessed thistle might decrease the effectiveness of H2-blockers.
There are reports that blessed thistle increases stomach acid.
Severity Minor Likelihood Possible Evidence D

Interaction 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.

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

Here's the simple version: famotidine (Pepcid) works by telling your stomach to make less acid, which is what calms heartburn, reflux, and ulcers. Blessed thistle is a bitter herb that does the opposite, it's thought to gently nudge your stomach into making more acid. So in theory, taking the two together could blunt some of the relief famotidine is giving you, and you might notice heartburn or sour stomach creeping back.

I want to keep this in perspective, though. This is rated a minor interaction based only on anecdotal reports, so it's far from a sure thing. If you do try blessed thistle and your symptoms return, just mention it to your pharmacist or doctor before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.

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

Blessed Thistle Also Interacts With Other Medications

Blessed Thistle has 35 minor known drug interactions in our database — the Famotidine one above is one of them. If you take anything else, check it against the full list below.

Minor 35 No known interaction 2,795 (incl. Famotidine)
Taking anything else?

Check Another of Your Medications Against Blessed Thistle

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

From our Q&A

Questions About Blessed Thistle or Famotidine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Blessed Thistle or Famotidine, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Famotidine

This page covers Blessed Thistle only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Famotidine page lists 41 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), African Wild Potato (moderate), Banderol (moderate), Beer (moderate) and Biofeedback (moderate).

By severity: 1 major · 19 moderate · 21 minor.

From our pharmacist’s overview on the Famotidine page

“Famotidine (Pepcid) treats heartburn and acid reflux, a low-stakes job most days, but its interaction list earns genuine caution because one entry is rated major. That entry is activated charcoal, which can bind famotidine in the gut and sharply cut how much of the drug reaches your blood.”

Reviewed by 2 · Jul 18, 2026

Open the Famotidine interaction page

One more smart check

Taking Blessed Thistle as Part of a Dietary Supplement Product? Check It for Interactions

We hold 729 real supplement products containing Blessed Thistle, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Blessed Thistle. Your product may carry other ingredients that interact with Famotidine too, on top of Blessed Thistle — 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 Blessed Thistle and Famotidine 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 Blessed Thistle
Top 25%

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

29 days ago today
Medication Famotidine
Top 5%

#102 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 Blessed Thistle

What is Blessed Thistle?

Blessed Thistle
  • Digestive upset and poor appetite
  • Boosting bile flow
  • General bitter tonic
  • Supporting milk supply during breastfeeding (traditional)
  • Wound care (traditional, topical)

Blessed thistle is a bitter herb traditionally used to stimulate appetite and ease mild digestive complaints. High-quality human studies are lacking, so its benefits are not well proven. It is likely fine for short-term use in small, food-like amounts, but it should be avoided in pregnancy and used with caution by people allergic to ragweed and related plants.

Read the full Blessed Thistle monograph & all interactions
Medication

About Famotidine

What Is Famotidine Used For?

Brand names: Pepcid, Famotidine, Pepcid AC, Famotidine Injection

Famotidine treats a range of acid-related conditions. Over-the-counter tablets (such as Acid Controller, Acid Reducer, Acid Relief, Amazon Basic Care Acid Reducer, Basic Care Acid Reducer, and Calmicid AC) relieve and prevent heartburn associated with acid indigestion and sour stomach.

Prescription-strength famotidine tablets and oral suspension are used for active duodenal ulcers (ulcers in the small intestine), active gastric ulcers (stomach ulcers), GERD — including erosive esophagitis (inflammation that damages the esophagus), and pathological hypersecretory conditions such as Zollinger-Ellison syndrome (a rare disorder causing the stomach to produce too much acid). The oral suspension is also indicated in children as young as newborns for GERD, and in children one year and older for peptic ulcer disease. Famotidine injection is used in hospitalized patients who cannot take oral medication.

See full Famotidine drug information
Keep checking

Other Drugs & Blessed Thistle

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

0Major
0Moderate
35Minor
2,794No known interaction
35 Minor 2,794 No interaction
Minor

35 interactions

No interaction 2,794 drugs checked — show the list

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

Showing the 60 most looked-up of 2,794 medications checked with no known interaction — see the full Blessed Thistle list.

See the full Blessed Thistle interactions page
See every supplement checked against Famotidine, 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
Blessed Thistle monograph › Uses, safety, and every drug interaction in one place Famotidine supplement interactions › Every supplement checked against Famotidine, ranked by severity Famotidine drug information › The full plain-English guide to this medication 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 Blessed Thistle and Famotidine Together: Common Questions

Can you take Blessed Thistle with Famotidine?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Blessed Thistle and Famotidine interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Famotidine and Blessed Thistle?

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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.