Drug & supplement interaction

Serrapeptase + Phenylephrine

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

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

We found no known interaction between Serrapeptase 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. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Serrapeptase 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 Serrapeptase 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.

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.

Serrapeptase safety at a glance

Serrapeptase overall Use caution Generally tolerated short-term, but long-term safety is not well studied.
Pregnancy Avoid Not enough safety data, so it is best avoided during pregnancy.
Breastfeeding Avoid No reliable safety information, so avoid while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Phenylephrine and Serrapeptase? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Phenylephrine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Phenylephrine is filed under 5 classifications — including alpha-adrenergic agonists, stimulant drugs, serotonergic drugs. Serrapeptase has documented interactions with 1 drug class — the most serious being anticoagulant/antiplatelet drugs (moderate) — and none of Phenylephrine’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Serrapeptase Does Interact With Other Medications

Serrapeptase has 122 moderate known drug interactions in our database — Phenylephrine isn’t one of them. If you take anything else, check it against the full list below.

Moderate 122 No known interaction 2,708 (incl. Phenylephrine)
Taking anything else?

Check Another of Your Medications Against Serrapeptase

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

What to actually watch for

No Interaction Found — But Data Suggests Serrapeptase and Phenylephrine May Share a Side Effect

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do.

  • Nausea reported in 7.6% of FDA reports for Phenylephrine Additional detail

    Serrapeptase

    “Orally, some patients have reported experiencing epigastric pain, gastrointestinal upset, and nausea; however, these side effects appear to occur at the same rate as placebo.”

    Serrapeptase · Natural Medicines adverse-effect record, reported in nausea and vomiting.

    1 source cited
    1. 13152. Mazzone A, Catalani M, Costanzo M, et al. Evaluation of Serratia peptidase in acute or chronic inflammation of otorhinolaryngology pathology: a multicentre, double-blind, randomized trial versus placebo. J Int Med Res 1990;18:379-88.. PubMed

    Phenylephrine

    Listed in the ADVERSE REACTIONS section of the FDA label for Phenylephrine, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for Serrapeptase but not commonly for Phenylephrine: stomach upset.

Effects for Phenylephrine come from the ADVERSE REACTIONS section of its FDA label; effects for Serrapeptase come from the Natural Medicines adverse-effect record, quoted above. 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. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

From our Q&A

Questions About Serrapeptase 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 Serrapeptase 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 Serrapeptase 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 Serrapeptase as Part of a Dietary Supplement Product? Check It for Interactions

We hold 9 real supplement products containing Serrapeptase, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Serrapeptase. Even though Serrapeptase 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 Serrapeptase 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 Serrapeptase
Top half

#663 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 Serrapeptase reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified October 4, 2026. The Serrapeptase and Phenylephrine records this page draws on were last updated July 10, 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 Serrapeptase

What is Serrapeptase?

  • Inflammation and swelling
  • Sinus and respiratory congestion
  • Pain after surgery or injury
  • Joint and back pain
  • Thinning mucus

Serrapeptase is an enzyme marketed to reduce inflammation, swelling, pain, and mucus, but the human evidence is limited and mostly low quality. If you want to try it, choose an enteric-coated product, follow the label, and check with your pharmacist or doctor first—especially if you are pregnant, breastfeeding, or take other medicines.

Enzyme produced by bacteria (Serratia species) found in silkworms · Tablets, capsules (often enteric-coated)

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

Serrapeptase: dosing

There is no official or well-established dose for serrapeptase. Products are often measured in enzyme "units" rather than simple milligrams, and these vary between brands.The best approach is to follow the directions on the product label and not exceed them.

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

Read the full Serrapeptase 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 & Serrapeptase

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

0Major
122Moderate
0Minor
2,707No known interaction
122 Moderate 2,707 No interaction
Moderate

122 interactions

Showing 60 of 122 moderate interactions — see all 122 on the Serrapeptase page.

No interaction 2,707 drugs checked — show the list

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

Showing the 60 most looked-up of 2,707 medications checked with no known interaction — see the full Serrapeptase list.

See the full Serrapeptase interactions page
See every supplement checked against Phenylephrine, ranked by severity
Evidence & sources

Serrapeptase References

The 2 references that drive our Serrapeptase 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. Tachibana M, Mizukoshi O, Harada Y, et al. A multi-centre, double-blind study of serrapeptase versus placebo in post-antrotomy buccal swelling. Pharmatherapeutica 1984;3:526-30..
  2. Mazzone A, Catalani M, Costanzo M, et al. Evaluation of Serratia peptidase in acute or chronic inflammation of otorhinolaryngology pathology: a multicentre, double-blind, randomized trial versus placebo. J Int Med Res 1990;18:379-88.. 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 Serrapeptase and Phenylephrine Together: Common Questions

Is it safe to take Serrapeptase with Phenylephrine?
We do not list a known interaction between Serrapeptase 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.
Do Serrapeptase and Phenylephrine have any of the same side effects?
Yes — our sources link each of them separately to one of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
How was the Serrapeptase and Phenylephrine combination checked?
Interactions in our licensed database are recorded against drug classes. Phenylephrine is filed under 5 classifications, and Serrapeptase has documented interactions with 1 drug class — none of Phenylephrine's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Serrapeptase interact with any other medications?
Yes. Serrapeptase has 122 documented drug interactions in our database — Phenylephrine is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Phenylephrine interact with any supplements?
Yes. Phenylephrine has documented interactions with 81 supplements in our database — Serrapeptase 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

Serrapeptase 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 2 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phenylephrine and Serrapeptase?

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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.