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Dietary supplement

Ostarin MK-2866 Ingredients & Drug Interactions

by Hardcore Formulations

Ostarin MK-2866 label
See full label image
Capsule Category: Non-nutrient/non-botanical
Most serious interaction: Moderate
Clinical methodology reviewed by · Updated Sep 16, 2026 · Label data from the NIH DSLD
What is this page for?

First and foremost: checking Ostarin MK-2866 against your medications. The heart of this page is the interaction checker and the full interaction report — how this product’s ingredients may interact with prescription and over-the-counter medicines you may be taking.

Around that, we add a pharmacist’s high-level view of the product as a whole — what’s inside, the evidence for its stated use, how transparent the label is, and what safety data exists — so you can see the full picture in one place. It’s educational information from our licensed clinical databases and the clinical staff at HelloPharmacist — not medical advice — and we don’t sell or endorse products. Our editorial policy

The interaction bottom line Most serious interaction: Moderate

Ostarin MK-2866 is a dietary supplement by Hardcore Formulations with 1 active ingredient. Its ingredients are commonly taken for muscle building, athletic performance, fat loss / body recomposition.Based on those ingredients, 611 medications have a known interaction with it, the most serious rated moderate. The ingredients most likely to interact are Select Androgen Receptor Modulator Ostarin-MK-2866. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

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Check Your Meds Against Ostarin MK-2866 by Hardcore Formulations

Ask about any prescription or over-the-counter medication and we check it for interactions with Ostarin MK-2866 by Hardcore Formulations — and tell you which ingredient is responsible.

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Computed from our clinical databases

HelloPharmacist Scorecard of Ostarin MK-2866 by Hardcore Formulations

Four independent checks of what is known — a summary of the available information, not a grade of the product itself.

Evidence for Intended Use
By FDA rules, dietary supplements can’t claim to treat, cure, or prevent disease — so labels speak in careful marketing language. We discern each product’s intended use from its name, label claims, and label statements, then grade the clinical evidence for that use. How these ratings are computed
Not assessable

The stated purpose hasn't been mapped to our evidence data yet.

Why this rating?
  • We haven't mapped this product's purpose to our evidence data yet — it'll be graded on the next content refresh.
Ingredient Transparency
Full

Every active ingredient lists its own amount on the label.

Why this rating?
  • The label discloses an exact amount for 1 of its 1 active ingredient.
  • No proprietary blends here — you can verify the dose of every single component.
Known Interaction Concern
Moderate identified

The most serious documented interaction for these ingredients is Moderate. Check your medications for a personalized result.

Why this rating?
  • 1 of the 1 matched ingredient can interact with medications — Ostarine.
  • The most serious interaction on file is rated Moderate.
  • For scale: 612 individual medications appear in the full list. A big number alone doesn't make a product dangerous — what matters is whether YOUR medication is on it, so run yours through the interaction checker on this page.
Safety Information
Well characterized

Adverse-effect, pregnancy, and general safety data are on file for most of these ingredients.

Why this rating?
  • We hold adverse-effect (side-effect) data for 1 of the 1 matched ingredient.
  • Pregnancy & breastfeeding safety ratings cover 1 of 1.
  • General safety write-ups exist for 1 of 1.
  • Remember: this measures how much safety information exists. Thin data is not the same as being safe.

HelloPharmacist summaryFully disclosed formula with no assessable stated purpose. Moderate medication interactions have been identified, and safety information is well characterized.

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Jan 25, 2020.

This Scorecard evaluates available label information, ingredient evidence, and known medication-safety considerations. It does not independently verify product identity, purity, potency, contamination, or manufacturing quality. How these ratings are computed

At a glance

General information

Key facts about Ostarin MK-2866, straight from the product label.

Brand Hardcore Formulations
Net contents 90 Capsule(s)
Market status Off market
Date entered into DSLD Jan 25, 2020
DSLD ID 211475
Product type Non-nutrient/non-botanical
Supplement form Capsule
Dietary claims / uses All Other
Intended target group(s) Adult (18 - 50 Years)
From the label
Everything in this section is reproduced from the manufacturer’s own product label — it’s the label speaking, not HelloPharmacist. We show it so you can see exactly what the maker states; we don’t verify or endorse those statements.

Supplement Facts

The label details for Ostarin MK-2866 by Hardcore Formulations, sourced from the NIH Dietary Supplement Label Database.

Supplement Facts

Daily Value (DV) Target Group(s):
Adults and children 4 or more years of age
Minimum serving Sizes:
2 Capsule(s)
Maximum serving Sizes:
2 Capsule(s)
Servings per container
45
IngredientAmount% DV
Select Androgen Receptor Modulator Ostarin-MK-286625 mg--

Other ingredients: Gelatin, Silica, Magnesium Stearate

Tap any ingredient to jump to its full detail below.

Label statements
These statements are the manufacturer’s wording, reproduced from the product label — the label is saying it, not HelloPharmacist. We don’t verify or endorse them.
General Statements

Sarm series

Clinical grade

Formulation

Lean muscle, joint repair, & fat loss

FDA Statement of Identity

Dietary Supplement

Is this label outdated? Report a formula or label change and our pharmacy team will review it.

See for yourself

Ostarin MK-2866 by Hardcore Formulations label

The label scan from the NIH Dietary Supplement Label Database. Tap to enlarge.

Ostarin MK-2866 label

Label images are published by the NIH Dietary Supplement Label Database for the version of this product on file. Always read your actual product label.

View the full label (PDF)
What’s inside

The Ingredients in Ostarin MK-2866 by Hardcore Formulations

This is the 1 active ingredient this product is made of. Select it to open its full monograph.

Serving size2 Capsule(s) Dosage formCapsule Servings per container45 Amounts shown are per serving.

Select Androgen Receptor Modulator Ostarin-MK-2866

Interacts with
611 drugs
25 mg per serving

Ostarine (also called MK-2866 or enobosarm) is an experimental, unapproved drug known as a SARM (selective androgen receptor modulator), not a true di...

Select Androgen Receptor Modulator Ostarin-MK-2866 monograph & interactions

Other (inactive) ingredients: Gelatin, Silica, Magnesium Stearate. These complete the product’s ingredient list but are not active constituents.

Interaction report

Ostarin MK-2866 by Hardcore Formulations Drug Interactions

Ostarin MK-2866 contains a single active ingredient, and it has known interactions with 611 medications. Here’s the picture, then you can look up your own drug.

Want to check YOUR meds against Ostarin MK-2866?

Ask about interactions with your drugs in plain English — “Can I take it with lisinopril?” — and we find you the answer in seconds, ingredient by ingredient.

 Go to the checker
611Drugs
440 Moderate 171 Minor

Ingredients driving the most interactions

Select Androgen Receptor Modulator Ostarin-MK-2866 611

Individual Drug Interactions

The ingredients in Ostarin MK-2866 interact with 611 drugs. Click any drug to see the details.

1 of the 1 ingredient in Ostarin MK-2866 interact with drugs. Each result below shows which ingredient is responsible. Select Androgen Receptor Modulator Ostarin-MK-2866

Each ingredient & the kinds of drugs it affects

For each ingredient in Ostarin MK-2866 with known interactions, here are the types of medications it can affect. Open any type for the detail — or search your exact drug in the checker above.

Select Androgen Receptor Modulator Ostarin-MK-28666 drug types · 611 drugs

Cytochrome P450 3A4 (Cyp3A4) Inducers

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%.

Likelihood Possible Evidence B
Hepatotoxic Drugs

Theoretically, concomitant use with hepatotoxic drugs might increase the risk of adverse hepatotoxic effects.
Some clinical research shows that ostarine can increase alanine aminotransferase, a marker of liver damage, in some patients. Additionally, the U.S. Food and Drug Administration warns that supplements containing SARMs, such as ostarine, have been associated with reports of liver toxicity and there are at least two reports of drug-induced liver injury attributed to the use of ostarine.

Likelihood Possible Evidence D
Probenecid (Benemid)

Theoretically, concomitant use of ostarine with probenecid could increase the effects and adverse effects of ostarine.
Clinical research shows that probenecid increases ostarine levels and slows the clearance of ostarine, likely via inhibition of UDP-glucuronosyltransferase (UGT). Ostarine is partially metabolized by UGT.

Likelihood Possible Evidence B
Rifampin (Rifadin)

Theoretically, concomitant use of ostarine with rifampin could decrease the clinical effects of ostarine.
Clinical research shows that taking rifampin with ostarine reduces the maximum plasma concentration of ostarine by 23% and the area under the curve by 43%. Ostarine is partially metabolized by cytochrome P450 3A4 (CYP3A4), and rifampin is a potent CYP3A4 inducer.

Likelihood Possible Evidence B
Cytochrome P450 2C9 (Cyp2C9) Substrates

Theoretically, ostarine might increase levels of drugs metabolized by CYP2C9, although clinical research suggests this is not clinically relevant.
Although in vitro research suggests that ostarine inhibits CYP2C9, more robust clinical research shows that ostarine does not significantly affect CYP2C9.

Likelihood Unlikely Evidence B
Cytochrome P450 3A4 (Cyp3A4) Inhibitors

Theoretically, concomitant use of ostarine with CYP3A4 inhibitors could increase the effects and adverse effects of ostarine, although this is unlikely to be clinically significant.
Ostarine is partially metabolized by CYP3A4. However, clinical research shows that taking itraconazole, a potent inhibitor of CYP3A4, had minimal effects on the levels of ostarine in the body.

Likelihood Unlikely Evidence B
Select Androgen Receptor Modulator Ostarin-MK-2866 full monograph & interactions
The maker

Brand information

Manufacturer and brand details for Ostarin MK-2866, from the product label.

Hardcore Formulations

See all Hardcore Formulations products
Name
Hardcore Formulations
Pharmacist Counseling Corner

Ostarin MK-2866 by Hardcore Formulations: Common Questions

Does Ostarin MK-2866 by Hardcore Formulations interact with any medications?
Yes. Based on its ingredients, Ostarin MK-2866 has a known interaction with 611 medications. Use the checker to see how it interacts with a specific drug.
How can one product interact with so many drugs?
Ostarin MK-2866 contains a single active ingredient, and that one ingredient can interact with many different medications on its own. We check it against each medication and show the mechanism responsible.
Where does this information come from?
The product label data comes from the NIH Dietary Supplement Label Database (DSLD); the interaction data is built on the Natural Medicines database and reviewed by HelloPharmacist pharmacists.

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

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Label information is sourced from the NIH Dietary Supplement Label Database and reflects the product version on file; always read your actual product label. This page is for education only and is not a substitute for professional medical advice. Confirm with your pharmacist or doctor before combining supplements and medications.

Ostarin MK-2866 label
Go deeper

The Full Monographs Behind Ostarin MK-2866’s Ingredients

Every ingredient we hold a full HelloPharmacist monograph for — uses, evidence, safety, and the complete interaction list.

Herb & supplement monograph

Ostarine

Interacts with 611 drugs

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...

Read the full Ostarine monograph →
Sources

Sources & How We Checked

Ostarin MK-2866's label data comes from the NIH Dietary Supplement Label Database; the ingredient interaction data is from the Natural Medicines database, reviewed by our pharmacists.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

The 10 references behind this product’s interaction data

Every citation that drives the interaction findings for this product’s ingredients, from the evidence-graded Natural Medicines (TRC Healthcare) database. Open an ingredient to browse its citations — links open the study on PubMed or the publisher’s site.

Ostarine 10 references
  1. Warning Letter: Ironmag Labs 10/23/17. FDA Inspections, Compliance, Enforcement, and Criminal Investigations, October 23, 2017. https://www.fda.gov/iceci/enforcementactions/warningletters/2017/ucm582464.htm Accessed: November 1, 2017
  2. Warning Letter: Panther Sports Nutrition 10/23/17. FDA Inspections, Compliance, Enforcement, and Criminal Investigations, October 23, 2017. https://www.fda.gov/iceci/enforcementactions/warningletters/2017/ucm581630.htm. Accessed: November 1, 2017
  3. Warning Letter: Infantry Labs LLC 10/23/17. FDA Inspections, Compliance, Enforcement, and Criminal Investigations, October 23, 2017. https://www.fda.gov/iceci/enforcementactions/warningletters/2017/ucm582685.htm. Accessed: November 1, 2017
  4. Dobs AS, Boccia RV, Croot CC, et al. Effects of enobosarm on muscle wasting and physical function in patients with cancer: a double-blind, randomised controlled phase 2 trial. Lancet Oncol 2013;14(4):335-45. PubMed
  5. Dalton JT, Barnette KG, Bohl CE, et al. The selective androgen receptor modulator GTx-024 (enobosarm) improves lean body mass and physical function in healthy elderly men and postmenopausal women: results of a double-blind, placebo-controlled phase II tri
  6. 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
  7. FDA. FDA Warns against using SARMs in body building products. October 2017. Available at: https://www.fda.gov/newsevents/newsroom/fdainbrief/ucm583021.htm.
  8. Bedi H, Hammond C, Sanders D, Yang HM, Yoshida EM. Drug-induced liver injury from enobosarm (ostarine), a selective androgen receptor modulator. ACG Case Rep J 2021;8(1):e00518. PubMed
  9. Kintz P, Gheddar L, Paradis C, et al. Peroxisome Proliferator-Activated Receptor Delta Agonist (PPAR- d) and Selective Androgen Receptor Modulator (SARM) Abuse: Clinical, Analytical and Biological Data in a Case Involving a Poisonous Combination of GW1516
  10. Weinblatt D, Roy S. Drug-Induced Liver Injury Secondary to Enobosarm: A Selective Androgen Receptor Modulator. J Med Cases 2022;13(5):244-248. PubMed

See these in context on the Ostarine monograph →

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

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