Drug & supplement interaction

Madagascar Periwinkle + Tolbutamide

Tolbutamide brand name: Orinase.

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

Madagascar Periwinkle has a moderate interaction with Tolbutamide. Animal research shows that Madagascar periwinkle lowers blood glucose levels in diabetic rats.

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

Madagascar Periwinkle and Tolbutamide

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

Moderate

ANTIDIABETES DRUGS

Why this applies to Tolbutamide

Tolbutamide falls under ANTIDIABETES DRUGS — the group Madagascar Periwinkle interacts with.

Animal research shows that Madagascar periwinkle lowers blood glucose levels in diabetic rats. Theoretically, using Madagascar periwinkle in combination with antidiabetes drugs might increase the risk of hypoglycemia; monitor blood glucose closely.
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 thing to keep in mind with tolbutamide (Orinase): its whole job is to lower your blood sugar by nudging your pancreas to release more insulin. In animal studies, Madagascar periwinkle also seemed to lower blood sugar. So the worry is that the two together could push your blood sugar down a little too far, which we call hypoglycemia.

If that happened, you might feel shaky, sweaty, dizzy, confused, or suddenly very hungry. I want to be honest, though: this is a theoretical concern based only on lab and animal research, not human studies. On top of that, the raw periwinkle plant is genuinely toxic and not safe to take on your own. Please don't start it, and check with your pharmacist or doctor before mixing anything new with tolbutamide.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Oguntibeju OO, Aboua Y, Goboza M. Vindoline-A natural product from catharanthus roseus reduces hyperlipidemia and renal pathophysiology in experimental type 2 diabetes. Biomedicines. 2019 Aug 13;7(3):59. 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

Madagascar Periwinkle Also Interacts With Other Medications

Madagascar Periwinkle has 86 moderate known drug interactions in our database — the Tolbutamide one above is one of them. If you take anything else, check it against the full list below.

Moderate 86 No known interaction 2,744 (incl. Tolbutamide)
Taking anything else?

Check Another of Your Medications Against Madagascar Periwinkle

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

Everything else you take

See Every Supplement That Interacts With Tolbutamide

This page covers Madagascar Periwinkle only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tolbutamide page lists 305 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), Adrafinil (moderate) and African Wild Potato (moderate).

By severity: 2 major · 255 moderate · 48 minor.

From our pharmacist’s overview on the Tolbutamide page

“People take tolbutamide (Orinase) to lower blood sugar in type 2 diabetes, and diabetes is exactly the condition supplement shelves target, which is why this list runs to 305 ingredients and deserves real caution. Of those, 239 also push glucose around, most often downward, so combining them can drive sugar lower than intended.”

Reviewed by 2 · Jul 18, 2026

Open the Tolbutamide interaction page

One more smart check

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

We hold 8 real supplement products containing Madagascar Periwinkle, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Madagascar Periwinkle. Your product may carry other ingredients that interact with Tolbutamide too, on top of Madagascar Periwinkle — 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 Madagascar Periwinkle and Tolbutamide 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 Madagascar Periwinkle
Top half

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

29 days ago today
Medication Tolbutamide
Steady interest

#1,619 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 Madagascar Periwinkle

What is Madagascar Periwinkle?

  • Diabetes (folk use)
  • High blood pressure (traditional use)
  • Sore throat and mouth ailments
  • Wound healing (topical)
  • Source of cancer chemotherapy drugs

Madagascar periwinkle is a flowering plant famous as the natural source of important chemotherapy drugs (vincristine and vinblastine), but the raw plant itself is toxic and not safe to use as a home remedy. While it has a long history in traditional medicine, there is no reliable evidence that taking the whole herb is safe or effective, and it should not be self-administered.

Read the full Madagascar Periwinkle monograph & all interactions
Medication

About Tolbutamide

What Is Tolbutamide Used For?

Brand name: Orinase

  • Tolbutamide is used along with diet and exercise, and sometimes with other medications, to treat type 2 diabetes (condition in which the body does not use insulin normally and, therefore, cannot control the amount of sugar in the blood). Tolbutamide is in a class of medications called sulfonylureas. Tolbutamide lowers blood sugar by causing the pancreas to produce insulin (a natural substance that is needed to break down sugar in the body) and helping the body use insulin efficiently. This medication will only help lower blood sugar in people whose bodies produce insulin naturally. Tolbutamide is not used to treat type 1 diabetes (condition in which the body does not produce insulin and, therefore, cannot control the amount of sugar in the blood) or diabetic ketoacidosis (a serious condition that may occur if high blood sugar is not treated).

  • Over time, people who have diabetes and high blood sugar can develop serious or life-threatening complications, including heart disease, stroke, kidney problems, nerve damage, and eye problems. Taking medication(s), making lifestyle changes (e.g., diet, exercise, quitting smoking), and regularly checking your blood sugar may help to manage your diabetes and improve your health. This therapy may also decrease your chances of having a heart attack, stroke, or other diabetes-related complications such as kidney failure, nerve damage (numb, cold legs or feet; decreased sexual ability in men and women), eye problems, including changes or loss of vision, or gum disease. Your doctor and other healthcare providers will talk to you about the best way to manage your diabetes.

See full Tolbutamide drug information
Keep checking

Other Drugs & Madagascar Periwinkle

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

0Major
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Madagascar Periwinkle page.

No interaction 2,743 drugs checked — show the list

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

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Madagascar Periwinkle list.

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

Can you take Madagascar Periwinkle with Tolbutamide?
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 Madagascar Periwinkle and Tolbutamide 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 Tolbutamide and Madagascar Periwinkle?

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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.