Drug & supplement interaction

Ostarine + Nafcillin Sodium

Nafcillin Sodium brand name: Unipen.

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

Ostarine has a moderate interaction with Nafcillin Sodium. Theoretically, concomitant use of ostarine with CYP3A4 inducers could decrease the clinical effects of ostarine.

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

Ostarine and Nafcillin Sodium

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

Moderate

CYTOCHROME P450 3A4 (CYP3A4) INDUCERS

Why this applies to Nafcillin Sodium

Nafcillin Sodium falls under CYTOCHROME P450 3A4 (CYP3A4) INDUCERS — the group Ostarine interacts with.

Theoretically, concomitant use of ostarine with CYP3A4 inducers could decrease the clinical effects of ostarine.
Ostarine is partially metabolized by CYP3A4. Clinical research shows that taking rifampin, a potent inducer of CYP3A4, reduces the maximum plasma concentration of ostarine by 23% and the area under the curve by 43%.
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 what's going on with this pair. Nafcillin is an antibiotic, but it also happens to rev up a liver enzyme called CYP3A4. Ostarine is partly broken down by that same enzyme. So when nafcillin speeds up CYP3A4, your body may clear ostarine faster, leaving less of it around. In studies with rifampin (a strong version of this kind of enzyme booster), ostarine levels dropped by about 23 to 43 percent. Nafcillin is a milder inducer, so the effect is likely smaller and is still mostly theoretical.

The practical point: the interaction would tend to weaken ostarine, not make it more dangerous. That said, I want to be straight with you, ostarine is an unapproved SARM that's been tied to liver injury and isn't something I'd recommend taking at all. Please talk this over with your pharmacist or doctor.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Coss CC, Jones A, Dalton JT. Pharmacokinetic drug interactions of the selective androgen receptor modulator GTx-024 (enobosarm) with itraconazole, rifampin, probenecid, celecoxib and rosuvastatin. Invest New Drugs 2016;34(4):458-67. 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

Ostarine Also Interacts With Other Medications

Ostarine has 439 moderate, 171 minor known drug interactions in our database — the Nafcillin Sodium one above is one of them. If you take anything else, check it against the full list below.

Moderate 439 Minor 171 No known interaction 2,220 (incl. Nafcillin Sodium)
Taking anything else?

Check Another of Your Medications Against Ostarine

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

Everything else you take

See Every Supplement That Interacts With Nafcillin Sodium

This page covers Ostarine only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Nafcillin Sodium page lists 75 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Asarabacca (major), Siberian Cocklebur (major), Alkanna (moderate) and Alpine Ragwort (moderate).

By severity: 3 major · 61 moderate · 11 minor.

From our pharmacist’s overview on the Nafcillin Sodium page

“Nafcillin sodium (Unipen) is a penicillin antibiotic for serious staph infections, often given by IV, so anything that weakens it or piles strain on the kidneys carries real weight. Three of the 75 supplements on this page rate major, and those come first: Siberian cocklebur and asarabacca can each damage the kidneys, and activated cha…”

Reviewed by 2 · Jul 18, 2026

Open the Nafcillin Sodium interaction page

One more smart check

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

We hold 33 real supplement products containing Ostarine, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Ostarine. Your product may carry other ingredients that interact with Nafcillin Sodium too, on top of Ostarine — 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 Ostarine and Nafcillin Sodium 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 Ostarine
Steady interest

#1,066 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Nafcillin Sodium
Steady interest

#2,353 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 Ostarine

What is Ostarine?

  • Muscle building
  • Athletic performance
  • Fat loss / body recomposition
  • Bodybuilding cycles

Ostarine (also called MK-2866 or enobosarm) is an experimental, unapproved drug known as a SARM (selective androgen receptor modulator), not a true dietary supplement. It is not approved by the FDA, is banned in sports, and has been linked to liver injury and other serious harms, so it is not recommended for general use.

Read the full Ostarine monograph & all interactions
Keep checking

Other Drugs & Ostarine

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

0Major
439Moderate
171Minor
2,219No known interaction
439 Moderate 171 Minor 2,219 No interaction
Moderate

439 interactions

Showing 60 of 439 moderate interactions — see all 439 on the Ostarine page.

Minor

171 interactions

Showing 60 of 171 minor interactions — see all 171 on the Ostarine page.

No interaction 2,219 drugs checked — show the list

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

Showing the 60 most looked-up of 2,219 medications checked with no known interaction — see the full Ostarine list.

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

Can you take Ostarine with Nafcillin Sodium?
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 Ostarine and Nafcillin Sodium 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 Nafcillin Sodium and Ostarine?

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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.