Interactions on record — worth a quick check against your medications. Check your meds →
Dietary supplement

S23 Ingredients & Drug Interactions

by Panther Sports Nutrition

S23 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 S23 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

S23 is a dietary supplement by Panther Sports Nutrition 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 (2S)-N-(4-cyano-3-(trifluoromethylphenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide. Use the checker below to test your specific medication, or read the full HelloPharmacist Interaction Report.

Jump to a section

Check Your Meds Against S23 by Panther Sports Nutrition

Ask about any prescription or over-the-counter medication and we check it for interactions with S23 by Panther Sports Nutrition — and tell you which ingredient is responsible.

Pharmacist-reviewed data Checks every ingredient Answer in seconds
Prefer a human? Send your question to our licensed pharmacists — free, answered by email within 24 hours.

HelloPharmacist Scorecard of S23 by Panther Sports Nutrition

Our pharmacy team’s full take, with four database checks built into the cards below — a summary of what is known, not a grade of the product itself.

From our pharmacy team — supplement deep dive

Generated from HelloPharmacist’s pharmacist-curated databases and editorial rules · Last generated Sep 10, 2026

What’s inside

Full disclosure
Ingredient Transparency · database check
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.

S23 contains one active ingredient: ostarine, a selective androgen receptor modulator (SARM) — a research compound that binds to androgen receptors in muscle and bone tissue. The product is completed with inactive ingredients: rice flour, magnesium stearate, and gelatin capsule material.

Does it work?

Not established
Evidence for Intended Use · database check
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 established

The graded evidence we hold for these ingredients covers different conditions than the ones this product is marketed for, so there's no established rating for its stated use — see Ostarine's own graded uses on its monograph.

Why this rating?
  • The label markets this product for: muscle building and fat loss.
  • We looked for evidence on: Athletic performance, Muscular dystrophy, Sarcopenia, body composition, lean mass.
  • The closest evidence on file: Ostarine is rated "Insufficient Reliable Evidence To Rate" for Athletic performance (Natural Medicines).
  • Also on file: Ostarine is rated "Insufficient Reliable Evidence To Rate" for Muscular dystrophy, Sarcopenia.

The evidence for ostarine's effectiveness is insufficient for any of its proposed uses. Our data shows ratings of insufficient reliable evidence to rate for athletic performance, breast cancer, cachexia (muscle wasting), muscular dystrophy, and sarcopenia (age-related muscle loss).

That means the science isn't established enough yet to say whether it works.

The evidence, ingredient by ingredient Ostarine

How safe is it?

Well-documented data
Safety Information · database check
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.

Ostarine is an unapproved investigational drug — it has not been cleared by the FDA and comes with documented safety risks. It is possibly unsafe when taken by mouth.

The most common side effects are abdominal pain, loss of appetite, constipation, diarrhea, and nausea. A small number of study participants experienced transient increases in liver enzymes (ALT), with higher rates at higher doses — in one study, about 21% of healthy older adults taking 3 mg daily showed ALT elevation.

Rare but serious liver toxicity has been reported. Because ostarine affects hormone pathways, it must be avoided during pregnancy.

There is no safety data for breastfeeding, so it should be avoided then as well.

Side effects, ingredient by ingredient Ostarine

Meds to double-check

Moderate interaction found
Known Interaction Concern · database check
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.

Before taking S23, check with your doctor or pharmacist if you take any medications that affect your liver (hepatotoxic drugs), any drugs that slow down CYP3A4 metabolism (such as itraconazole or ketoconazole for fungal infections), rifampin or rifabutin (tuberculosis), probenecid (gout), or any drugs broken down by CYP3A4 or CYP2C9 enzymes. No interactions are documented for CYP2C9 substrates in clinical practice, but the theoretical risk exists.

Check your own medication Run your meds through the checker above

The bottom line

Scorecard at a glanceFully disclosed formula with no established evidence rating for its marketed use. Moderate medication interactions have been identified, and safety information is well characterized.

S23 is an unapproved research compound with uncertain benefits and known risks to your liver and hormone system. It interacts significantly with many medications.

If you're considering it, this is a conversation to have with your doctor or pharmacist — they can review your specific health situation and medications and help you decide whether it's right for you.

Educational only — not medical advice; always confirm with your pharmacist. Our editorial policy · How we use AI

Assessment coverage: 1 of 1 active ingredient matched to our full ingredient reviews (monographs). Based on the product label dated Dec 22, 2019.

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 S23, straight from the product label.

Brand Panther Sports Nutrition
Net contents 90 Capsule(s)
Market status On market
Date entered into DSLD Dec 22, 2019
DSLD ID 209999
Product type Non-nutrient/non-botanical
Supplement form Capsule
Dietary claims / uses Structure/Function
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 S23 by Panther Sports Nutrition, 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:
1 Capsule(s)
Maximum serving Sizes:
1 Capsule(s)
Servings per container
90
IngredientAmount% DV
(2S)-N-(4-cyano-3-(trifluoromethylphenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide15 mg--

Other ingredients: Rice Flour, Magnesium Stearate, Gelatin

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.
Formulation

Fast muscle builder Burn fat fast Mass builder

FDA Statement of Identity

Hardcore Supplement Performance Supplement

Suggested/Recommended/Usage/Directions

Suggested Use: Take 1 capsule twice a day. Do not take for more than 2 months consecutively. Take at least 1 month off before starting another cycle. For Best Results: Eat 5-6 smaller meals per day Reduce daily carbohydrate intake Eliminate fast food and soda from your diet

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

See for yourself

S23 by Panther Sports Nutrition label

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

S23 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 S23 by Panther Sports Nutrition

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

Serving size1 Capsule(s) Dosage formCapsule Servings per container90 Amounts shown are per serving.

(2S)-N-(4-cyano-3-(trifluoromethylphenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide

Interacts with
611 drugs
15 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...

(2S)-N-(4-cyano-3-(trifluoromethylphenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide monograph & interactions

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

Interaction report

S23 by Panther Sports Nutrition Drug Interactions

Want to check YOUR meds against S23?

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

(2S)-N-(4-cyano-3-(trifluoromethylphenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide 611

Individual Drug Interactions

The ingredients in S23 interact with 611 drugs. Click any drug to see the details.

1 of the 1 ingredient in S23 interact with drugs. Each result below shows which ingredient is responsible. (2S)-N-(4-cyano-3-(trifluoromethylphenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide

Each ingredient & the kinds of drugs it affects

For each ingredient in S23 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.

(2S)-N-(4-cyano-3-(trifluoromethylphenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide6 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
(2S)-N-(4-cyano-3-(trifluoromethylphenyl)-3-(3-fluoro-4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide full monograph & interactions
The maker

Brand information

Manufacturer and brand details for S23, from the product label.

Panther Sports Nutrition

See all Panther Sports Nutrition products
Name
Panther Sports Nutrition
Pharmacist Counseling Corner

S23 by Panther Sports Nutrition: Common Questions

Does S23 by Panther Sports Nutrition interact with any medications?
Yes. Based on its ingredients, S23 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?
S23 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.
Is ostarine approved by the FDA?
No. Ostarine is an unapproved investigational drug. The FDA has not cleared it for any use, and it carries documented safety risks.
What are the most common side effects?
Abdominal pain, loss of appetite, constipation, diarrhea, and nausea are the most common. A small percentage of people taking ostarine have experienced temporary increases in liver enzymes, with the rate rising at higher doses.
Can I take S23 if I'm pregnant or breastfeeding?
No. Ostarine must be avoided during pregnancy because it affects hormone pathways. There is no safety data for breastfeeding, so it should be avoided then too. Talk with your doctor or pharmacist about alternatives.
Does ostarine actually build muscle or improve athletic performance?
The evidence isn't established. Our data shows insufficient reliable evidence to rate ostarine for athletic performance, muscle-building, or any of its other proposed uses. You'd be taking it without clear proof it works.
What's the difference between S23 and other SARMs?
The product facts we hold cover ostarine only, so we can't compare it to other SARMs. Your pharmacist or doctor can discuss how different compounds work.

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

Not sure if S23 is safe with your meds?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.

S23 label
Go deeper

The Full Monographs Behind S23’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

S23'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

Keep exploring
Supplement interaction checker › Check any supplement or product against your medications Drug–drug interactions › Check two or more of your medications against each other Browse medications A–Z › Every drug we've checked against herbs & supplements NDC & pricing lookup › Find a drug’s NDCs, packaging and costs Ask a pharmacist › Free, personal answer from our licensed team