Drug & supplement interaction

S-23 + Phenylephrine

Phenylephrine brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen.

No Known Interaction
Medically reviewed by · Updated June 2026 · Pair last verified Oct 4, 2026
The bottom line No known interaction

We found no known interaction between S-23 and Phenylephrine 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.

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Interaction report

S-23 and Phenylephrine

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 Phenylephrine 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 Phenylephrine, 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 Phenylephrine and S-23? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Phenylephrine’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 Phenylephrine’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. 3 of them are worth acting on rather than waiting out — marked below.

  • A slow heartbeat Worth acting on
  • Shortness of breath Worth acting on mentioned in 6.2% of FDA reports for Phenylephrine
  • Raised blood pressure Worth acting on
  • Blurred vision
  • Headache mentioned in 7.8% of FDA reports for Phenylephrine
  • Nausea mentioned in 7.6% of FDA reports for Phenylephrine
  • Vomiting

From the ADVERSE REACTIONS section of the FDA label for Phenylephrine. Read the label on DailyMed › Where a percentage is shown, it is the share of 221,388 voluntary FDA FAERS reports for Phenylephrine 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

From our Q&A

Questions About S-23 or Phenylephrine

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers S-23 or Phenylephrine, 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 Phenylephrine

This page covers S-23 only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Phenylephrine page lists 81 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Ephedra (major), Lithium (major), Peyote (major) and Rauvolfia Vomitoria (major).

By severity: 6 major · 60 moderate · 15 minor.

From our pharmacist’s overview on the Phenylephrine page

“If you take phenylephrine (Sudafed PE, Biorphen) for congestion, treat this list as one that needs real attention, since six of its 81 entries carry a major rating. Phenylephrine tightens blood vessels to clear your nose, and more than half of the interactions here come from stimulant ingredients, ephedra above all, that can push blood…”

Reviewed by 2 · Jul 18, 2026

Open the Phenylephrine 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 Phenylephrine, 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 Phenylephrine 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

#1,344 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Phenylephrine
Top 25%

#668 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 October 4, 2026. The S-23 and Phenylephrine 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 .
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 Phenylephrine

What Is Phenylephrine Used For?

Brand names: Gilchew, AH Chew D, Gilchew IR, Sudafed PE, Biorphen

Phenylephrine is used in several different products, and each one has its own use.

Injection (IV): raises blood pressure in adults with clinically important hypotension (low blood pressure) caused mainly by widened blood vessels. Some injections are labeled for anesthesia only. Others are labeled for anesthesia and septic shock.

Eye drops: Phenylephrine Hydrochloride Ophthalmic Solution is used to dilate the pupil.

Nasal products: temporarily relieve nasal and sinus congestion from the common cold, hay fever or other upper respiratory allergies.

Rectal suppositories: relieve itching, burning and discomfort from hemorrhoids and temporarily shrink hemorrhoidal tissue.

Most-Reported Side Effects for Phenylephrine

From FAERS, the FDA’s public side-effect reporting system (221,388 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Fatigue 20,609 reports
Headache 17,301 reports
Nausea 16,925 reports
Diarrhea 14,221 reports
Dyspnea 13,719 reports
See full Phenylephrine 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 Phenylephrine, 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.

  1. 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 Phenylephrine Together: Common Questions

Is it safe to take S-23 with Phenylephrine?
We do not list a known interaction between S-23 and Phenylephrine. 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.
Does Phenylephrine interact with any supplements?
Yes. Phenylephrine has documented interactions with 81 supplements in our database — S-23 is not one of them. The Phenylephrine 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 Phenylephrine drug information The full plain-English guide to this medication Phenylephrine supplement interactions Every supplement checked against Phenylephrine, 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 Phenylephrine and S-23?

Our pharmacists answer your medication & supplement questions — free.

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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.