Drug & supplement interaction

Evening Primrose + Indomethacin

Indomethacin brand names: Indocin, Indocin SR, Indo-Lemmon, Indomethagan, Tivorbex.

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

Evening Primrose has a minor interaction with Indomethacin. Theoretically, evening primrose may increase the levels and clinical effects of CYP2C9 substrates.

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

Evening Primrose and Indomethacin

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

Minor

CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES

Why this applies to Indomethacin

Indomethacin falls under CYTOCHROME P450 2C9 (CYP2C9) SUBSTRATES — the group Evening Primrose interacts with.

Theoretically, evening primrose may increase the levels and clinical effects of CYP2C9 substrates.
In vitro research shows that linoleic acid, a constituent of evening primrose oil, inhibits CYP2C9.
Severity Minor 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 CYP2C9 to help break down indomethacin. Lab studies suggest that linoleic acid, found in evening primrose oil, may slow that enzyme down a bit. If that happened in real life, indomethacin could hang around at slightly higher levels, which might mean more of the usual side effects, like stomach upset, heartburn, headache, dizziness, or a higher chance of stomach irritation.

The good news is that this concern is theoretical, based on test-tube data rather than people, so most folks won't notice anything. Indomethacin is already a strong anti-inflammatory on its own, so I'd just mention this combo to your pharmacist or doctor and watch for any extra side effects before changing anything.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Zou L, Harkey MR, and Henderson GL. Effects of herbal components on cDNA-expressed cytochrome P450 enzyme catalytic activity. Life Sci 8-16-2002;71(13):1579-1589. 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

Evening Primrose Also Interacts With Other Medications

Evening Primrose has 148 moderate, 85 minor known drug interactions in our database — the Indomethacin one above is one of them. If you take anything else, check it against the full list below.

Moderate 148 Minor 85 No known interaction 2,597 (incl. Indomethacin)
Taking anything else?

Check Another of Your Medications Against Evening Primrose

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

From our Q&A

Questions About Evening Primrose or Indomethacin

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

This page covers Evening Primrose only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Indomethacin page lists 100 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Beer (major), Siberian Cocklebur (major) and Wine (major).

By severity: 5 major · 68 moderate · 27 minor.

Open the Indomethacin interaction page

One more smart check

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

We hold 98 real supplement products containing Evening Primrose, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Evening Primrose. Your product may carry other ingredients that interact with Indomethacin too, on top of Evening Primrose — 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 Evening Primrose and Indomethacin 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 Evening Primrose
Top 25%

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

29 days ago today
Medication Indomethacin
Steady interest

#1,912 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 Evening Primrose

What is Evening Primrose?

Evening Primrose
  • Eczema and skin health
  • PMS symptoms
  • Breast pain (mastalgia)
  • Menopause symptoms
  • Inflammation
  • Diabetic nerve pain

Evening primrose oil is a seed oil rich in gamma-linolenic acid (GLA), an omega-6 fatty acid, that is popularly used for skin conditions, PMS, and breast pain. The evidence behind most of these uses is mixed or weak, and it is not proven to be a reliable treatment for any condition. It is generally well tolerated for short-term use, but talk to your pharmacist or doctor before starting it, especially if you are pregnant or have a bleeding disorder.

Read the full Evening Primrose monograph & all interactions
Medication

About Indomethacin

What Is Indomethacin Used For?

Brand names: Indocin, Indocin SR, Indo-Lemmon, Indomethagan, Tivorbex

Indocin oral suspension and Indocin suppositories are used for moderate to severe rheumatoid arthritis (including acute flares), moderate to severe ankylosing spondylitis, and moderate to severe osteoarthritis. They are also used for acute painful shoulder (bursitis and/or tendinitis) and acute gouty arthritis.

Indomethacin for Injection is different. It is given intravenously to close a hemodynamically significant patent ductus arteriosus (a blood vessel near the heart that stays open) in premature infants weighing 500 to 1,750 g, when 48 hours of usual medical management has not worked.

See full Indomethacin drug information
Keep checking

Other Drugs & Evening Primrose

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

0Major
148Moderate
85Minor
2,596No known interaction
148 Moderate 85 Minor 2,596 No interaction
Moderate

148 interactions

Showing 60 of 148 moderate interactions — see all 148 on the Evening Primrose page.

Minor

85 interactions

Showing 60 of 85 minor interactions — see all 85 on the Evening Primrose page.

No interaction 2,596 drugs checked — show the list

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

Showing the 60 most looked-up of 2,596 medications checked with no known interaction — see the full Evening Primrose list.

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

Can you take Evening Primrose with Indomethacin?
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 Evening Primrose and Indomethacin 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 Indomethacin and Evening Primrose?

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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.