Drug & supplement interaction

Madagascar Periwinkle + Insulin Degludec

Insulin Degludec brand name: Tresiba.

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

Madagascar Periwinkle has a moderate interaction with Insulin Degludec. 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 Insulin Degludec

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

Moderate

ANTIDIABETES DRUGS

Why this applies to Insulin Degludec

Insulin Degludec 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 simple version: Tresiba (insulin degludec) already does one main job, it lowers your blood sugar steadily over a long stretch of time. Madagascar periwinkle, in animal studies, also seemed to push blood sugar down. So if you stacked the two together, the worry is that your sugar could drop too low, which we call hypoglycemia. That can show up as shakiness, sweating, dizziness, confusion, or in severe cases passing out.

I want to be honest about the evidence here: this is based on lab and rat studies, not solid human data, so it's more of a theoretical caution than a proven problem. Still, the raw plant itself is toxic and not something to take at home. Please check with your pharmacist or doctor before combining anything new with your insulin.

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 Insulin Degludec 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. Insulin Degludec)
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 Insulin Degludec

This page covers Madagascar Periwinkle only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Insulin Degludec page lists 239 supplements it has a documented interaction with, worst first, each one explained.

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

By severity: 1 major · 208 moderate · 30 minor.

From our pharmacist’s overview on the Insulin Degludec page

“Insulin degludec (Tresiba) is a long-acting insulin meant to hold blood sugar steady around the clock, which means anything else that pushes glucose down can push it too far. That is the story for nearly all 239 ingredients on this page, and the list warrants genuine caution.”

Reviewed by 2 · Jul 18, 2026

Open the Insulin Degludec 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 Insulin Degludec 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 Insulin Degludec 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

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

29 days ago today
Medication Insulin Degludec
Steady interest

#1,902 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 Insulin Degludec (rDNA Origin) Injection

What Is Insulin Degludec (rDNA Origin) Injection Used For?

Brand name: Tresiba

Insulin degludec (brand name Tresiba) is used to improve blood sugar (glucose) control in adults and children 1 year of age and older who have diabetes mellitus — including both type 1 and type 2 diabetes.

It is not recommended for treating diabetic ketoacidosis (a dangerous complication of diabetes that requires a different type of treatment). In people with type 1 diabetes, insulin degludec must always be used together with a short-acting insulin.

See full Insulin Degludec (rDNA Origin) Injection 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 Insulin Degludec, 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 Insulin Degludec supplement interactions › Every supplement checked against Insulin Degludec, ranked by severity Insulin Degludec (rDNA Origin) Injection 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 Insulin Degludec Together: Common Questions

Can you take Madagascar Periwinkle with Insulin Degludec?
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 Insulin Degludec 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 Insulin Degludec 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.