Drug & supplement interaction

Holy Basil + Metformin

Metformin brand names: Glucophage, Metformin.

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

Holy Basil has a moderate interaction with Metformin. Theoretically, holy basil might increase the risk of hypoglycemia when taken with antidiabetes drugs.

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

Holy Basil and Metformin

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

Moderate

ANTIDIABETES DRUGS

Why this applies to Metformin

Metformin falls under ANTIDIABETES DRUGS — the group Holy Basil interacts with.

Theoretically, holy basil might increase the risk of hypoglycemia when taken with antidiabetes drugs.
Small clinical studies show that taking holy basil can decrease fasting blood glucose and other measures of glycemic control in patients with type 2 diabetes.
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 simple version: holy basil seems to have its own mild blood-sugar-lowering effect. A few small studies in people with type 2 diabetes found that tulsi lowered fasting blood sugar. So when you pair it with metformin, the two may stack up and push your numbers lower than metformin alone would.

Metformin by itself rarely causes true lows, but combined with holy basil you could be more likely to notice hypoglycemia symptoms like shakiness, sweating, dizziness, or feeling unusually tired. The evidence here is limited and lower-quality, so this isn't a reason to panic. If you'd like to try tulsi, check with your pharmacist or doctor first, keep an eye on your home glucose readings, and watch for any low-sugar signs.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Agrawal P, Rai V, Singh RB. Randomized placebo-controlled, single blind trial of holy basil leaves in patients with noninsulin-dependent diabetes mellitus. Int J Clin Pharmacol Ther 1996;34:406-9.
  2. Somasundaram G, Manimekalai K, Salwe KJ, Pandiamunian J. Evaluation of the antidiabetic effect of Ocimum sanctum in type 2 diabetes patients. Int J Life Sci Pharma Res 2012;2(3):75-81.

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

Holy Basil Also Interacts With Other Medications

Holy Basil has 211 moderate known drug interactions in our database — the Metformin one above is one of them. If you take anything else, check it against the full list below.

Moderate 211 No known interaction 2,619 (incl. Metformin)
Taking anything else?

Check Another of Your Medications Against Holy Basil

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

From our Q&A

Questions About Holy Basil or Metformin

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

This page covers Holy Basil only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Metformin page lists 258 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Siberian Cocklebur (major), Acai (moderate), African Wild Potato (moderate) and Agaricus Mushroom (moderate).

By severity: 2 major · 217 moderate · 39 minor.

From our pharmacist’s overview on the Metformin page

“Siberian cocklebur is the ingredient I most want anyone taking metformin (Glucophage) to know about. It has caused severe low blood sugar in people, documented in humans, and it should not be combined with any glucose-lowering medication.”

Reviewed by 2 · Jul 18, 2026

Open the Metformin interaction page

One more smart check

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

We hold 1,867 real supplement products containing Holy Basil, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Holy Basil. Your product may carry other ingredients that interact with Metformin too, on top of Holy Basil — 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 Holy Basil and Metformin 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 Holy Basil
Top 25%

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

29 days ago today
Medication Metformin
Top 1%

#29 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 Holy Basil

What is Holy Basil?

Holy Basil
  • Stress and anxiety
  • Blood sugar support
  • Respiratory complaints
  • General immune and wellness support
  • Inflammation

Holy basil (tulsi) is a traditional Ayurvedic herb most often used today for stress and general wellness, but the human evidence is mostly small and preliminary. It is generally well tolerated by most adults, but it should be avoided in pregnancy and used cautiously by anyone with health conditions or taking medications. Talk to your pharmacist or doctor before starting it.

Read the full Holy Basil monograph & all interactions
Medication

About Metformin

What Is Metformin Used For?

Brand names: Glucophage, Metformin

Metformin is used to improve blood sugar (glucose) control in people with type 2 diabetes mellitus. It is always used together with diet and exercise, not instead of them.

Metformin hydrochloride tablets and oral solution are approved for adults and children 10 years and older. Metformin hydrochloride extended-release tablets — including brands such as Fortamet, Glumetza, and Metformin Hydrochloride Extended Release — are approved for adults only.

See full Metformin drug information
Keep checking

Other Drugs & Holy Basil

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

0Major
211Moderate
0Minor
2,618No known interaction
211 Moderate 2,618 No interaction
Moderate

211 interactions

Showing 60 of 211 moderate interactions — see all 211 on the Holy Basil page.

No interaction 2,618 drugs checked — show the list

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

Showing the 60 most looked-up of 2,618 medications checked with no known interaction — see the full Holy Basil list.

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

Can you take Holy Basil with Metformin?
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 Holy Basil and Metformin 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 Metformin and Holy Basil?

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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.