Drug & supplement interaction

Berberine + Timolol

Timolol brand names: Blocadren, Timol, Timoptic.

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

Timolol falls into 2 drug categories that Berberine can interact with; the most serious is rated moderate. Theoretically, berberine might have additive effects with antihypertensive drugs.

Read the full interaction report
SeverityModerate
LikelihoodPossible
Interactions2
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Berberine and Timolol

These two interact in 2 distinct ways. Each one is explained separately below.

Why Are There 2 Interactions?

Berberine interacts with whole categories of medication. Timolol falls into 2 of those categories, so it can interact with Berberine in 2 different ways. We’ve listed each one below — your overall risk is driven by the most serious of them (Moderate).

Moderate

ANTIHYPERTENSIVE DRUGS

1 of 2

Why this applies to Timolol

Timolol falls under ANTIHYPERTENSIVE DRUGS — the group Berberine interacts with.

Theoretically, berberine might have additive effects with antihypertensive drugs.
Animal research suggests that berberine can have hypotensive effects. Also, a clinical study suggests that taking berberine in combination with amlodipine can lower systolic and diastolic blood pressure when compared with amlodipine alone.
Severity Moderate 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: berberine on its own seems to nudge blood pressure down a little, and Timolol already does the same job by slowing your heart rate and relaxing blood vessels. Put them together and the effects may stack up, so your blood pressure (or pulse) could dip lower than expected. That might leave you feeling lightheaded, tired, or dizzy when you stand up quickly.

I'll be honest about the evidence here. This is mostly theoretical, built on animal studies and one human trial using a different blood pressure drug, not Timolol specifically. So it's not a reason to panic. Still, if you're thinking about adding berberine, loop in your pharmacist or doctor first and keep an eye on your readings at home.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Sabir M and Bhide NK. Study of some pharmacological actions of berberine. Ind J Physiol & Pharmac 1971;15(3):111-132.
  2. Chun YT, Yip TT, Lau KL, and et al. A biochemical study on the hypotensive effect of berberine in rats. Gen Pharmac 1979;10:177-182. PubMed
  3. Lan J, Zhao Y, Dong F, et al. Meta-analysis of the effect and safety of berberine in the treatment of type 2 diabetes mellitus, hyperlipemia and hypertension. J Ethnopharmacol. 2015;161:69-81. PubMed
Moderate

CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES

2 of 2

Timolol also falls under CYTOCHROME P450 2D6 (CYP2D6) SUBSTRATES.

Theoretically, berberine might increase serum levels of drugs metabolized by CYP2D6.
In vitro research and preliminary clinical evidence show that berberine can inhibit CYP2D6. Theoretically, use of berberine with drugs metabolized by CYP2D6 might increase drug levels and increase the risk of adverse effects.
Severity Moderate Likelihood Possible Evidence B

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 gist for timolol. Your liver uses an enzyme called CYP2D6 to help clear timolol from your body. Berberine appears to slow that enzyme down, so timolol could clear more slowly and build up a bit higher than usual. Timolol is an active drug (not a prodrug), so more of it in your system usually means a stronger effect.

In real life that might show up as a heart rate that runs too slow, lower blood pressure, lightheadedness, or feeling unusually tired. Keep in mind this is mostly theoretical and based on lab work plus some early human data, so it's a 'watch for it,' not a panic. Please don't change anything on your own. Just check with your pharmacist or doctor before adding berberine.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Chatterjee P, Franklin MR. Human cytochrome p450 inhibition and metabolic-intermediate complex formation by goldenseal extract and its methylenedioxyphenyl components. Drug Metab Dispos 2003;31:1391-7. PubMed
  2. Guo, Y., Chen, Y., Tan, Z. R., Klaassen, C. D., and Zhou, H. H. Repeated administration of berberine inhibits cytochromes P450 in humans. Eur J Clin Pharmacol 2012;68(2):213-217. PubMed
  3. Hermann, R. and von, Richter O. Clinical evidence of herbal drugs as perpetrators of pharmacokinetic drug interactions. Planta Med 2012;78(13):1458-1477. 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

Berberine Also Interacts With Other Medications

Berberine has 1 major, 1,158 moderate known drug interactions in our database — the Timolol one above is among them. If you take anything else, check it against the full list below.

Major 1 Moderate 1,158 No known interaction 1,671 (incl. Timolol)
Taking anything else?

Check Another of Your Medications Against Berberine

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

From our Q&A

Questions About Berberine or Timolol

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Berberine or Timolol, 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 Timolol

This page covers Berberine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Timolol page lists 183 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Indian Snakeroot (major) and Tyramine (major).

By severity: 5 major · 151 moderate · 27 minor.

From our pharmacist’s overview on the Timolol page

“The supplement list for timolol (Blocadren, Timoptic) calls for genuine care, starting with its five major-rated entries. Timolol is a beta-blocker that slows the heart and lowers blood pressure, and even the eye-drop form absorbs enough to matter.”

Reviewed by 2 · Jul 18, 2026

Open the Timolol interaction page

One more smart check

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

We hold 908 real supplement products containing Berberine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Berberine. Your product may carry other ingredients that interact with Timolol too, on top of Berberine — 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 Berberine and Timolol 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 Berberine
Top 10%

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

29 days ago today
Medication Timolol
Steady interest

#1,700 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 Berberine

What is Berberine?

Berberine
  • Blood sugar control
  • High cholesterol
  • Heart and metabolic health
  • Digestive upset
  • Antimicrobial support
  • Weight management

Berberine is a yellow plant compound that has shown promise for lowering blood sugar and cholesterol in some studies, but the quality of research varies and it is not a replacement for prescribed medicine. It can cause stomach upset and should be avoided during pregnancy and breastfeeding. Always check with your pharmacist or doctor before starting it, especially if you take other medications.

Read the full Berberine monograph & all interactions
Medication

About Timolol

What Is Timolol Used For?

Brand names: Blocadren, Timol, Timoptic

Timolol is available in ophthalmic (eye) forms and as an oral tablet, and each form has its own approved uses. Ophthalmic formulations — including Betimol, Istalol, Timolol GFS, Timolol hemihydrate, Timolol Maleate eye drops, and Timolol Maleate Ophthalmic Gel Forming Solution — are used to lower elevated intraocular pressure (pressure inside the eye) in people with ocular hypertension or open-angle glaucoma.

Timolol Maleate tablets are used orally for three separate conditions: treating high blood pressure (alone or combined with other blood pressure medicines), reducing the risk of death and repeat heart attack in people who have survived a heart attack and are clinically stable, and preventing migraine headaches.

See full Timolol drug information
Keep checking

Other Drugs & Berberine

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

1Major
1,158Moderate
0Minor
1,670No known interaction
1 Major 1,158 Moderate 1,670 No interaction
Major

1 interaction

Moderate

1,158 interactions

Showing 60 of 1,158 moderate interactions — see all 1,158 on the Berberine page.

No interaction 1,670 drugs checked — show the list

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

Showing the 60 most looked-up of 1,670 medications checked with no known interaction — see the full Berberine list.

See the full Berberine interactions page
See every supplement checked against Timolol, 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
Berberine monograph › Uses, safety, and every drug interaction in one place Timolol supplement interactions › Every supplement checked against Timolol, ranked by severity Timolol 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 Berberine and Timolol Together: Common Questions

Can you take Berberine with Timolol?
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.
Why are there 2 interactions listed for Berberine and Timolol?
Timolol belongs to more than one drug category, and Berberine interacts with each of those categories a little differently. We list every one so nothing is missed — your overall risk is driven by the most serious of them.
How serious is the Berberine and Timolol 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 Timolol and Berberine?

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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.