Drug & supplement interaction

Rosemary + Tizanidine

Tizanidine brand names: Zanaflex, Ontralfy.

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

Rosemary has a minor interaction with Tizanidine. Theoretically, rosemary might decrease the levels and clinical effects of CYP1A2 substrates.

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

Rosemary and Tizanidine

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

Minor

CYTOCHROME P450 1A2 (CYP1A2) SUBSTRATES

Why this applies to Tizanidine

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

Theoretically, rosemary might decrease the levels and clinical effects of CYP1A2 substrates.
In vitro research shows that rosemary induces CYP1A2 enzymes. This effect has not been reported in humans.
Severity Minor Likelihood Unlikely Evidence D

Interaction has been demonstrated in animal or in lab research but has been shown not to occur in humans..

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the gist: your body relies on an enzyme called CYP1A2 to clear tizanidine out of your system. In test-tube studies, rosemary appears to speed that enzyme up a bit. If that happened in real life, your body might break down tizanidine a little faster, which could mean less muscle-relaxing effect, so a bit more of the stiffness or spasms you're trying to control.

The good news is this is purely theoretical. It has only been seen in lab and animal research, never confirmed in people, and the herb amounts you'd get from cooking are very unlikely to matter. Concentrated rosemary supplements are the bigger question mark. If you're taking those regularly, just mention it to your pharmacist or doctor so they can keep an eye on how well your tizanidine is working.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Debersac P, Heydel JM, Amiot MJ, et al. Induction of cytochrome P450 and/or detoxication enzymes by various extracts of rosemary: description of specific patterns. Food Chem Toxicol 2001;39(9):907-18. PubMed
  2. Debersac P, Vernevaut MF, Amiot MJ, et al. Effects of a water-soluble extract of rosemary and its purified component rosmarinic acid on xenobiotic-metabolizing enzymes in rat liver. Food Chem Toxicol 2001;39(2):109-17. 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

Rosemary Also Interacts With Other Medications

Rosemary has 212 moderate, 159 minor known drug interactions in our database — the Tizanidine one above is one of them. If you take anything else, check it against the full list below.

Moderate 212 Minor 159 No known interaction 2,459 (incl. Tizanidine)
Taking anything else?

Check Another of Your Medications Against Rosemary

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

From our Q&A

Questions About Rosemary or Tizanidine

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

This page covers Rosemary only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Tizanidine page lists 143 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), Arsenic (major), Beer (major) and Cesium (major).

By severity: 11 major · 101 moderate · 31 minor.

Open the Tizanidine interaction page

One more smart check

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

We hold 1,786 real supplement products containing Rosemary, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Rosemary. Your product may carry other ingredients that interact with Tizanidine too, on top of Rosemary — 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 Rosemary and Tizanidine 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 Rosemary
Top 25%

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

29 days ago today
Medication Tizanidine
Steady interest

#1,866 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 Rosemary

What is Rosemary?

Rosemary
  • Memory and concentration
  • Digestive upset
  • Hair growth
  • Anxiety and stress (aromatherapy)
  • Muscle and joint discomfort
  • Antioxidant support

Rosemary is a fragrant Mediterranean herb that is safe and flavorful in normal food amounts. Some early research suggests possible benefits for memory, mood, and hair growth, but the evidence is limited and far from conclusive. Concentrated supplements and the essential oil should be used carefully, and the essential oil should never be swallowed.

Read the full Rosemary monograph & all interactions
Medication

About Tizanidine

What Is Tizanidine Used For?

Brand names: Zanaflex, Ontralfy

Tizanidine — available as tablets, capsules, and as the oral solution Ontralfy — is used to manage spasticity (abnormal muscle stiffness or spasms). Because it works for a relatively short window of time, it is typically scheduled around the activities when spasm relief matters most.

Ontralfy (oral solution) and Zanaflex capsules are specifically indicated for the treatment of spasticity in adults. Other tizanidine tablets and capsules are indicated for the management of spasticity more broadly.

See full Tizanidine drug information
Keep checking

Other Drugs & Rosemary

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

0Major
212Moderate
159Minor
2,458No known interaction
212 Moderate 159 Minor 2,458 No interaction
Moderate

212 interactions

Showing 60 of 212 moderate interactions — see all 212 on the Rosemary page.

Minor

159 interactions

Showing 60 of 159 minor interactions — see all 159 on the Rosemary page.

No interaction 2,458 drugs checked — show the list

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

Showing the 60 most looked-up of 2,458 medications checked with no known interaction — see the full Rosemary list.

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

Can you take Rosemary with Tizanidine?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Rosemary and Tizanidine interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About Tizanidine and Rosemary?

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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.