Drug & supplement interaction

Catechu + Mexiletine

Mexiletine brand name: Mexitil.

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

Catechu has a moderate interaction with Mexiletine. Theoretically, black catechu may increase the levels and clinical effects of CYP1A2 substrates.

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

Catechu and Mexiletine

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

Moderate

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

Why this applies to Mexiletine

Mexiletine falls under CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES — the group Catechu interacts with.

Theoretically, black catechu may increase the levels and clinical effects of CYP1A2 substrates.
Animal research shows that black catechu can increase theophylline concentrations in the blood, possibly by inhibiting CYP1A2. Theophylline is a CYP1A2 substrate.
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 gist: your body relies on a liver enzyme called CYP1A2 to break down mexiletine. Catechu is rich in tannins that, at least in lab and animal studies, can slow that same enzyme down. If CYP1A2 is working slower, mexiletine may not clear as quickly and could build up in your blood.

Why that matters: mexiletine is a heart rhythm medicine with a fairly narrow safety window, so even modest increases can be a concern. Too much can bring on nausea, tremor, dizziness, lightheadedness, or in some cases worsening of the very arrhythmias it's meant to control. That said, this is theoretical and only seen with a related drug in animals, not proven in people. Still, please loop in your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Al-Mohizea AM, Raish M, Ahad A, et al. Pharmacokinetic interaction of Acacia catechu with CYP1A substrate theophylline in rabbits. J Tradit Chin Med 2015;35(5):588-93. 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

Catechu Also Interacts With Other Medications

Catechu has 474 moderate known drug interactions in our database — the Mexiletine 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. Mexiletine)
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.

Everything else you take

See Every Supplement That Interacts With Mexiletine

This page covers Catechu only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Mexiletine page lists 152 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), 1,3-dmaa (moderate), Acacia Rigidula (moderate), Active Hexose Correlated Compound (ahcc) (moderate) and Adrafinil (moderate).

By severity: 1 major · 107 moderate · 44 minor.

From our pharmacist’s overview on the Mexiletine page

“Mexiletine (Mexitil) steadies the heart's rhythm, and its benefit depends on holding a fairly precise blood level, so the 152 supplements on this list deserve real attention rather than a shrug. Only one entry, activated charcoal, is rated major, because it can soak up the drug in the gut and cut how much actually reaches your bloodstr…”

Reviewed by 2 · Jul 18, 2026

Open the Mexiletine 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 Mexiletine 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 Mexiletine 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

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

29 days ago today
Medication Mexiletine
Top half

#1,061 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 Mexiletine

What Is Mexiletine Used For?

Brand name: Mexitil

Mexiletine Hydrochloride capsules are indicated for the treatment of documented, life-threatening ventricular arrhythmias — for example, sustained ventricular tachycardia (a dangerously fast heart rhythm originating in the lower chambers). Because mexiletine itself can trigger arrhythmias, it is not recommended for minor or symptom-free irregular heartbeats.

Treatment is started in a hospital setting so heart rhythm can be monitored closely. Antiarrhythmic drugs, including mexiletine, have not been shown to improve overall survival in patients with ventricular arrhythmias.

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

Can you take Catechu with Mexiletine?
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 Mexiletine 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 Mexiletine and Catechu?

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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.