Drug & supplement interaction

Herb Robert + 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 Herb Robert 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.

Know someone taking this? Share
Facebook Post Reddit Email
On this page
Interaction report

Herb Robert 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 Herb Robert 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 Herb Robert 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.

Herb Robert safety at a glance

Herb Robert overall Use caution Generally used in small amounts traditionally, but human safety data are very limited.
Pregnancy Avoid Not enough safety information, so it is best avoided during pregnancy.
Breastfeeding Avoid No reliable safety data exist for nursing mothers, so avoid use.

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

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

What Herb Robert Itself Has Been Linked To

This is not an interaction — nothing below involves Phenylephrine. It is the side-effect record for Herb Robert on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Herb Robert, this list is the first place to look. One entry is worth acting on rather than waiting out — marked below.

  • A severe skin reaction Worth acting on Additional detail

    “Topically, Herb Robert can cause contact dermatitis. There are at least two cases of known contact sensitization of elderly individuals to Herb Robert through gardening. One case resulted in an erythema multiforme-like eruption requiring treatment with steroids.”

    Herb Robert · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 99144. Svendsen MT, Andersen KE, Thormann H, Paulsen E. Contact sensitization to Geranium robertianum L. in an amateur gardener. Contact Dermatitis. 2015;72(6):420-1.
    2. 99146. Badaoui A, Pecquet C, Fargeas C, Mahé E. Contact dermatitis caused by Geranium robertianum with erythema multiforme-like reaction. Contact Dermatitis. 2017;77(6):423-424.
  • A skin rash Additional detail

    “There is currently a limited amount of information on the adverse effects of Herb Robert. Topically, Herb Robert has been reported to cause allergic contact dermatitis.”

    Herb Robert · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 99144. Svendsen MT, Andersen KE, Thormann H, Paulsen E. Contact sensitization to Geranium robertianum L. in an amateur gardener. Contact Dermatitis. 2015;72(6):420-1.
    2. 99146. Badaoui A, Pecquet C, Fargeas C, Mahé E. Contact dermatitis caused by Geranium robertianum with erythema multiforme-like reaction. Contact Dermatitis. 2017;77(6):423-424.

Everything above comes from the Natural Medicines adverse-effect record for Herb Robert — expand a row for the licensed statement it rests on. We read the ADVERSE REACTIONS section of Phenylephrine’s FDA label too, and the two lists don’t meaningfully overlap — which is why no Phenylephrine column appears here.

From our Q&A

Questions About Herb Robert 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 Herb Robert 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 Herb Robert 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 Herb Robert 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 Herb Robert
Steady interest

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

29 days ago today
Medication Phenylephrine
Top 25%

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

What is Herb Robert?

Herb Robert
  • Digestive upset
  • Wound and skin care
  • Sore throat and mouth irritation
  • Respiratory complaints
  • General 'detox' tonic

Herb Robert is a traditional European herb used for digestion, wounds, and minor inflammation, but there is very little human research to confirm it works for any condition. It is likely fine in small amounts as a tea for most healthy adults, but its safety has not been well studied. Talk to your pharmacist or doctor before using it, and avoid it during pregnancy and breastfeeding.

Geranium robertianum · Geraniaceae · Above-ground parts (leaves, stems, and flowers) · Tea, tincture, dried herb, capsules, fresh poultice

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

Herb Robert: dosing

There is no established, standardized dose for Herb Robert. Traditional use involved brewing a small amount of the dried herb as a tea or applying crushed fresh leaves to the skin, but these amounts were not measured in a consistent, science-based way.If you choose to use a commercial product, follow the directions on the label and do not exceed the recommended amount.

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

Read the full Herb Robert 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 & Herb Robert

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

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

Herb Robert References

The 3 references that drive our Herb Robert 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. Svendsen MT, Andersen KE, Thormann H, Paulsen E. Contact sensitization to Geranium robertianum L. in an amateur gardener. Contact Dermatitis. 2015;72(6):420-1.
  2. Panahi Y, Akhavan A, Sahebkar A, et al. Investigation of the effectiveness of Syzygium aromaticum, Lavandula angustifolia and Geranium robertianum essential oils in the treatment of acute external otitis: a comparative trial with ciprofloxacin. J Microbi PubMed
  3. Badaoui A, Pecquet C, Fargeas C, Mahé E. Contact dermatitis caused by Geranium robertianum with erythema multiforme-like reaction. Contact Dermatitis. 2017;77(6):423-424.

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 Herb Robert and Phenylephrine Together: Common Questions

Is it safe to take Herb Robert with Phenylephrine?
We do not list a known interaction between Herb Robert 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 — Herb Robert 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

Herb Robert 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 3 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Phenylephrine and Herb Robert?

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.