Drug & supplement interaction

Oscillococcinum + 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 Oscillococcinum 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

Oscillococcinum 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 Oscillococcinum 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 Oscillococcinum 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.

Oscillococcinum safety at a glance

Oscillococcinum overall Use caution Generally well tolerated, but evidence of benefit is lacking and it should not replace proven flu care.
Pregnancy Use caution Safety has not been well studied in pregnancy, so check with your doctor first.
Breastfeeding Use caution Little data exists during breastfeeding, so use only with medical guidance.

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

Still wondering about combining Phenylephrine and Oscillococcinum? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Oscillococcinum 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.

  • Headache reported in 7.8% of FDA reports for Phenylephrine Additional detail

    Oscillococcinum

    “Orally, oscillococcinum has been associated with one report of headache in one clinical study.”

    Oscillococcinum · Natural Medicines adverse-effect record, reported in cluster headache.

    1 source cited
    1. 19063. Papp R, Schuback G, Beck E, et al. Oscillococcinum in patients with influenza-like syndromes: a placebo-controlled double-blind evaluation. British Homoeopathic Journal 1998;87:69-76.

    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 Oscillococcinum but not commonly for Phenylephrine: a severe allergic reaction.

Effects for Phenylephrine come from the ADVERSE REACTIONS section of its FDA label; effects for Oscillococcinum 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 Oscillococcinum 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 Oscillococcinum 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 Oscillococcinum 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

How much people look this up

Where Oscillococcinum 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 Oscillococcinum
Steady interest

#1,310 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 Oscillococcinum reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified October 4, 2026. The Oscillococcinum 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 Oscillococcinum

What is Oscillococcinum?

  • Flu-like symptoms
  • Common cold symptoms
  • Body aches and chills
  • Fatigue during illness
  • Fever associated with the flu

Oscillococcinum is a homeopathic product made from extremely diluted duck liver and heart, marketed to ease flu-like symptoms. High-quality research has not shown it works better than a placebo, but it is generally well tolerated. If you choose to try it, see it as a low-risk option rather than a proven treatment, and don't use it to replace a flu vaccine or needed medical care.

Anas barbariae hepatis et cordis extractum · Highly diluted extract of duck liver and heart (Muscovy duck) · Oral pellets/granules that dissolve under the tongue

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

Oscillococcinum: dosing

There is no scientifically established effective dose for Oscillococcinum, since it has not been shown to work. If you choose to use it, follow the directions on the product label exactly.The pellets are typically dissolved under the tongue rather than swallowed with water, and packages often suggest starting at the first sign of symptoms.

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

Read the full Oscillococcinum 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 & Oscillococcinum

Browse every other medication we’ve checked against Oscillococcinum — 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 Oscillococcinum 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 Oscillococcinum list.

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

Oscillococcinum References

The 2 references that drive our Oscillococcinum 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. Papp R, Schuback G, Beck E, et al. Oscillococcinum in patients with influenza-like syndromes: a placebo-controlled double-blind evaluation. British Homoeopathic Journal 1998;87:69-76.
  2. Azmi Y, Rao M, Verma I, Agrawal A. Oscillococcinum leading to angioedema, a rare adverse event. BMJ Case Rep. 2015 Jun 2;2015. 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 Oscillococcinum and Phenylephrine Together: Common Questions

Is it safe to take Oscillococcinum with Phenylephrine?
We do not list a known interaction between Oscillococcinum 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 Oscillococcinum 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.
Does Phenylephrine interact with any supplements?
Yes. Phenylephrine has documented interactions with 81 supplements in our database — Oscillococcinum 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

Oscillococcinum 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 Oscillococcinum?

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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.