Drug & supplement interaction

Caffeic Acid + 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 Caffeic Acid 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

Caffeic Acid 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 Caffeic Acid 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.

Caffeic Acid safety at a glance

Caffeic Acid overall Use caution Generally well tolerated in food amounts, but concentrated supplement doses are not well studied in humans.
Pregnancy Avoid Not enough safety data on supplement doses; best to avoid beyond normal dietary intake.
Breastfeeding Avoid Safety of supplement doses is unknown, so avoid unless your doctor advises otherwise.

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

Still wondering about combining Phenylephrine and Caffeic Acid? 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. Caffeic Acid has documented interactions with 3 drug classes — the most serious being organic anion transporter 1 (oat1) substrates (moderate), organic anion transporter 3 (oat3) substrates (moderate) and levodopa (minor) — 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

Caffeic Acid Does Interact With Other Medications

Caffeic Acid has 177 moderate, 5 minor 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 177 Minor 5 No known interaction 2,648 (incl. Phenylephrine)
Taking anything else?

Check Another of Your Medications Against Caffeic Acid

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

What to actually watch for

What Phenylephrine’s Own FDA Label Lists

This is not an interaction — none of it involves Caffeic Acid. 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. Caffeic Acid’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Caffeic Acid side to compare — that is a limit of the record, not a statement that Caffeic Acid has no side effects.

From our Q&A

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

We hold 20 real supplement products containing Caffeic Acid, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Caffeic Acid. Even though Caffeic Acid 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 Caffeic Acid 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 Caffeic Acid
Top half

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

29 days ago today
Medication Phenylephrine
Top 25%

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

What is Caffeic Acid?

  • Antioxidant support
  • General anti-inflammatory use
  • Skin and sun protection (topical)
  • Immune support
  • Cancer-prevention interest (research stage)

Caffeic acid is a natural plant compound found in coffee, many fruits, vegetables, and herbs, and it is studied mainly for its antioxidant and anti-inflammatory properties. Most evidence comes from laboratory and animal research, so its benefits in people are not yet proven. If you want to take it as a supplement, talk with your pharmacist or doctor first.

Naturally occurring plant compound (found in coffee, fruits, and many herbs) · Capsules, tablets, powders, and as part of plant extracts (such as coffee or propolis)

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

Caffeic Acid: dosing

There is no established standard dose of caffeic acid as a supplement. Research studies have used different amounts, and a safe, effective dose for general use has not been confirmed.If you choose to use a product that contains caffeic acid, follow the directions on the label and do not exceed the recommended amount.

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

Read the full Caffeic Acid 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 & Caffeic Acid

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

0Major
177Moderate
5Minor
2,647No known interaction
177 Moderate 5 Minor 2,647 No interaction
Moderate

177 interactions

Showing 60 of 177 moderate interactions — see all 177 on the Caffeic Acid page.

Minor

5 interactions

No interaction 2,647 drugs checked — show the list

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

Showing the 60 most looked-up of 2,647 medications checked with no known interaction — see the full Caffeic Acid list.

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

Caffeic Acid References

The 2 references that drive our Caffeic Acid 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. Uwai Y, Ozeki Y, Isaka T, et al. Inhibitory effect of caffeic acid on human organic anion transporters hOAT1 and hOAT3: a novel candidate for food-drug interaction. Drug Metab Pharmacokinet 2011;26:486-93. PubMed
  2. Wang LH, Hsu KY, Uang YS, et al. Caffeic acid improves the bioavailability of L-dopa in rabbit plasma. Phytother Res 2010;24:852-8.

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 Caffeic Acid and Phenylephrine Together: Common Questions

Is it safe to take Caffeic Acid with Phenylephrine?
We do not list a known interaction between Caffeic Acid 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.
How was the Caffeic Acid and Phenylephrine combination checked?
Interactions in our licensed database are recorded against drug classes. Phenylephrine is filed under 5 classifications, and Caffeic Acid has documented interactions with 3 drug classes — 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 Caffeic Acid interact with any other medications?
Yes. Caffeic Acid has 182 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 — Caffeic Acid 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

Caffeic Acid 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 Caffeic Acid?

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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.