Drug & supplement interaction

S-23 + Gemcitabine

Gemcitabine brand name: Gemzar.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated June 2026 · Pair last verified Sep 20, 2026

The bottom line No known interaction

We found no known interaction between S-23 and Gemcitabine in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

Know someone taking this? Share

Facebook Post Reddit Email

On this page

Interaction report

S-23 and Gemcitabine

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Gemcitabine and S-23 in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for S-23 at all — not against Gemcitabine, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

S-23 safety at a glance

S-23 overall Avoid S-23 is an unapproved experimental drug with no human safety data and known hormonal risks.

Pregnancy Possibly Unsafe When used orally or parenterally. The U.S. Food and Drug Administration and other regulatory agencies warn that dietary supplements containing selective androge... Read the full pregnancy detail

Breastfeeding Possibly Unsafe When used orally or parenterally. The U.S. Food and Drug Administration and other regulatory agencies warn that dietary supplements containing selective androge... Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Gemcitabine and S-23? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

What to actually watch for

What Gemcitabine’s Own FDA Label Lists

This is not an interaction — none of it involves S-23. These are the most notable effects listed in the ADVERSE REACTIONS section of Gemcitabine’s own FDA label, for the medication by itself. Knowing the drug’s own list makes it easier to work out the likely cause if something new turns up while you take both. 10 of them are worth acting on rather than waiting out — marked below.

A stroke or mini-stroke Worth acting on
A heart attack Worth acting on
A low platelet count Worth acting on mentioned in 7.0% of FDA reports for Gemcitabine
An irregular heartbeat Worth acting on
Anemia Worth acting on mentioned in 5.8% of FDA reports for Gemcitabine
A low white blood cell count Worth acting on mentioned in 6.2% of FDA reports for Gemcitabine
Kidney problems Worth acting on
Raised blood pressure Worth acting on
Shortness of breath Worth acting on
Liver problems Worth acting on

Showing the 10 most notable of 16 label-listed effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

From the ADVERSE REACTIONS section of the FDA label for Gemcitabine. Read the label on DailyMed › Where a percentage is shown, it is the share of 53,020 voluntary FDA FAERS reports for Gemcitabine that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. S-23’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no S-23 side to compare — that is a limit of the record, not a statement that S-23 has no side effects.

Special populations

S-23 in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Unsafe

When used orally or parenterally. The U.S. Food and Drug Administration and other regulatory agencies warn that dietary supplements containing selective androgen receptor modulators (SARMs) are dangerous. Avoid using.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

Overlapping uses

What Gemcitabine Is Prescribed For, and What S-23 Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Gemcitabine is a prescription medicine with approved uses on its FDA label. S-23 is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Gemcitabine is prescribed for: Gemcitabine Injection (available as Avgemsi, Gemcitabine, and Infugem) is used to treat several types of cancer. It is given in combination with carboplatin for advanced ovarian cancer that has returned at least 6 months after platinum-based treatment, and in combination with paclitaxel as a first-line treatment for metastatic breast cancer after prior chemotherapy with an anthracycline (a specific class of chemo drug). It is also given in combination with cisplatin for non-small cell lung cancer (NSCLC) that cannot be removed surgically or has spread. For pancreatic cancer that is locally advanced or has spread, it is used as a single agent — including in patients who have already been treated with fluorouracil.

S-23 has been studied for:

Breast cancer studied, not established S-23 has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

S-23 for breast cancer

Although there is interest in using oral S-23 for breast cancer, there is insufficient reliable information about the clinical effects of S-23 for this condition.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Gemcitabine on your own; if you are taking S-23 for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

Everything else you take

See Every Supplement That Interacts With Gemcitabine

This page covers S-23 only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Gemcitabine page lists 39 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Beer (major), Siberian Cocklebur (major), Wine (major), Ashwagandha (moderate) and Black Cohosh (moderate).

By severity: 3 major · 35 moderate · 1 minor.

Open the Gemcitabine interaction page

One more smart check

Taking S-23 as Part of a Dietary Supplement Product? Check It for Interactions

We hold 5 real supplement products containing S-23, each one broken down to its full ingredient list — and combination products often carry several ingredients besides S-23. Even though S-23 itself has no known interaction with Gemcitabine, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where S-23 and Gemcitabine 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 S-23

Steady interest

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

29 days ago today

Medication Gemcitabine

Steady interest

#2,588 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.

Where does our data come from?

Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every S-23 reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The S-23 and Gemcitabine records this page draws on were last updated June 22, 2026.
What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.

Data structure & sourcing designed and verified by Dr. Brian Staiger, PharmD, BCPS.

Supplement

About S-23

What is S-23?

Muscle building
Fat loss
Athletic performance enhancement
Body recomposition
Investigational male contraceptive (research only)

S-23 is an experimental, non-prescription synthetic drug called a selective androgen receptor modulator (SARM), not a dietary supplement, herb, or natural product. It has never been approved for human use, has not been proven safe in people, and is banned in sports; we do not recommend using it.

Not applicable; S-23 is a synthetic chemical compound · Liquid solutions, capsules, and powders sold as 'research chemicals'

An interaction check asks whether these two react with each other — it does not ask whether S-23 is a good idea for someone in your situation. Here is what our S-23 record says about it on its own.

S-23: dosing

There is no established or safe dose of S-23 for humans. It has never gone through the clinical testing that would set a safe and effective dose, so any amounts shared online are unverified and potentially dangerous.We do not provide dosing guidance for S-23 because doing so could imply it is safe to use, which it is not.

From our S-23 monograph — the full record covers uses, side effects and every documented interaction.

Read the full S-23 monograph & all interactions

Medication

About Gemcitabine Injection

What Is Gemcitabine Injection Used For?

Brand name: Gemzar

Gemcitabine Injection (available as Avgemsi, Gemcitabine, and Infugem) is used to treat several types of cancer. It is given in combination with carboplatin for advanced ovarian cancer that has returned at least 6 months after platinum-based treatment, and in combination with paclitaxel as a first-line treatment for metastatic breast cancer after prior chemotherapy with an anthracycline (a specific class of chemo drug).

It is also given in combination with cisplatin for non-small cell lung cancer (NSCLC) that cannot be removed surgically or has spread. For pancreatic cancer that is locally advanced or has spread, it is used as a single agent — including in patients who have already been treated with fluorouracil.

Most-Reported Side Effects for Gemcitabine

From FAERS, the FDA’s public side-effect reporting system (53,020 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Disease progression 4,850 reports

Thrombocytopenia 3,706 reports

Neutropenia 3,295 reports

Anemia 3,084 reports

Malignant neoplasm progression 2,912 reports

See full Gemcitabine Injection drug information

Keep checking

Other Drugs & S-23

Browse every other medication we’ve checked against S-23 — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major

0Moderate

0Minor

2,829No known interaction

2,829 No interaction

No interaction 2,829 drugs checked — show the list

We also checked S-23 against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full S-23 list.

See the full S-23 interactions page

See every supplement checked against Gemcitabine, ranked by severity

Evidence & sources

S-23 References

The 1 references that drive our S-23 monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

Joseph JF, Parr MK. Synthetic androgens as designer supplements. Curr Neuropharmacol. 2015;13(1):89-100. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking S-23 and Gemcitabine Together: Common Questions

Is it safe to take S-23 with Gemcitabine?

We do not list a known interaction between S-23 and Gemcitabine. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.

Are S-23 and Gemcitabine used for the same thing?

They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for S-23 in each. That is a conversation for your prescriber, especially if Gemcitabine is being adjusted to a target.

Does Gemcitabine interact with any supplements?

Yes. Gemcitabine has documented interactions with 39 supplements in our database — S-23 is not one of them. The Gemcitabine interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

S-23 monograph Uses, safety profile, and every drug interaction in one place Gemcitabine Injection drug information The full plain-English guide to this medication Gemcitabine supplement interactions Every supplement checked against Gemcitabine, 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 References The 1 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Gemcitabine and S-23?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.