Drug & supplement interaction

Catechu + Timolol

Timolol brand names: Blocadren, Timol, Timoptic.

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

Catechu has a moderate interaction with Timolol. Theoretically, concomitant use with antihypertensive drugs might increase the risk of hypotension.

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

Catechu and Timolol

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

Moderate

ANTIHYPERTENSIVE DRUGS

Why this applies to Timolol

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

Theoretically, concomitant use with antihypertensive drugs might increase the risk of hypotension.
Catechu might lower blood pressure.
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 basic idea: Timolol already works to bring your blood pressure down and slow your heart rate. Some lab and animal research suggests Catechu may have a mild blood-pressure-lowering effect of its own. Stacked together, the worry is that your pressure could dip a little lower than intended.

If that happened, you might feel dizzy, lightheaded, unusually tired, or notice your heartbeat feels slow, especially when you stand up quickly. I want to be honest, though: this is a theoretical concern based only on early studies, not real human reports, so for most people it stays minor. Still, if you'd like to try Catechu, run it by your pharmacist or doctor first and keep an eye on how you feel.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Sham JS, Chiu KW, Pang PK. Hypotensive action of Acacia catechu. Planta Med 1984;50:177-80.

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

Catechu Also Interacts With Other Medications

Catechu has 474 moderate known drug interactions in our database — the Timolol one above is one of them. If you take anything else, check it against the full list below.

Moderate 474 No known interaction 2,356 (incl. Timolol)
Taking anything else?

Check Another of Your Medications Against Catechu

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

From our Q&A

Questions About Catechu 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 Catechu 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 Catechu 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 Catechu as Part of a Dietary Supplement Product? Check It for Interactions

We hold 122 real supplement products containing Catechu, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Catechu. Your product may carry other ingredients that interact with Timolol too, on top of Catechu — 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 Catechu 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 Catechu
Top half

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

29 days ago today
Medication Timolol
Steady interest

#1,624 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 Catechu

What is Catechu?

Catechu
  • Mouth and throat soreness
  • Diarrhea and digestive upset
  • Skin wounds and bleeding gums
  • Astringent gargles and rinses
  • Traditional remedy for inflammation

Catechu is an astringent extract made from the heartwood of the Acacia (Senegalia) catechu tree, used traditionally for mouth sores, sore throat, diarrhea, and minor skin problems. Strong human evidence is lacking for most uses, so it should be viewed as a traditional remedy rather than a proven treatment. Talk to your pharmacist or doctor before using it, especially if you are pregnant, breastfeeding, or taking other medicines.

Read the full Catechu monograph & all interactions
Medication

About Timolol

What Is Timolol Used For?

Brand names: Blocadren, Timol, Timoptic

Timolol eye drops lower raised pressure inside the eye in people with ocular hypertension or open-angle glaucoma. This is the use for every eye product listed, including Timoptic, Timoptic-XE, Istalol, Betimol and Timolol GFS.

Timolol Maleate tablets (taken by mouth) have different uses. They treat high blood pressure, reduce the risk of death and repeat heart attack in stable patients who have survived the acute phase of a heart attack, and help prevent migraine headaches.

See full Timolol drug information
Keep checking

Other Drugs & Catechu

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

0Major
474Moderate
0Minor
2,355No known interaction
474 Moderate 2,355 No interaction
Moderate

474 interactions

Showing 60 of 474 moderate interactions — see all 474 on the Catechu page.

No interaction 2,355 drugs checked — show the list

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

Showing the 60 most looked-up of 2,355 medications checked with no known interaction — see the full Catechu list.

See the full Catechu 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
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Pharmacist Counseling Corner

Taking Catechu and Timolol Together: Common Questions

Can you take Catechu 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.
How serious is the Catechu 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 Catechu?

Our pharmacists answer your medication & supplement questions — free.

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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.