Drug & supplement interaction

Blood Type Diet + Phenylephrine

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

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated June 2026 · Pair last verified Oct 4, 2026

The bottom line No known interaction

We found no known interaction between Blood Type Diet 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

Blood Type Diet 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 Blood Type Diet in our sources. This does not guarantee that the combination is completely free of risk — research on Blood Type Diet alongside specific medications may be limited.

Worth understanding: our licensed dataset holds no drug-interaction record for Blood Type Diet 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.

Blood Type Diet is an eating pattern rather than something you take. Ask your pharmacist or doctor before changing how you eat while on a prescribed medicine: some medicines are dosed around meals, and a change in diet can change how they work. 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.

Blood Type Diet safety at a glance

Blood Type Diet overall Use caution The diet itself is generally food-based, but restricting whole food groups may lead to nutrient gaps.

Pregnancy Use caution Restrictive eating plans may limit needed nutrients during pregnancy; check with your doctor first.

Breastfeeding Use caution Avoid overly restrictive versions while nursing and ensure adequate calories and nutrients.

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

Still wondering about combining Phenylephrine and Blood Type Diet? 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 Blood Type Diet. 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 follow Blood Type Diet and take the medicine. 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. Blood Type Diet’s licensed record lists no adverse effects our clinical vocabulary could match, so there is no Blood Type Diet side to compare — that is a limit of the record, not a statement that Blood Type Diet has no side effects.

From our Q&A

Questions About Blood Type Diet 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 Blood Type Diet 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 Blood Type Diet 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 Blood Type Diet 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 Blood Type Diet

Steady interest

#1,396 of 1,452 supplements looked up here in the last 7 days

29 days ago today

Medication Phenylephrine

Top 25%

#507 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 Blood Type Diet reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified October 4, 2026. The Blood Type Diet 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 Dr. Brian Staiger, PharmD, BCPS.

Eating pattern

About Blood Type Diet

What is Blood Type Diet?

Weight loss
General wellness
Heart health
Digestive health
Reducing inflammation

The Blood Type Diet claims that eating foods matched to your ABO blood type improves health and weight, but good-quality studies have not shown that blood type determines who benefits from a given diet. Any health improvements people see are more likely from simply eating more whole, unprocessed foods. Talk to a pharmacist or doctor before making big changes, especially if you have a health condition.

Eating plan (whole-food diet based on ABO blood type)

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

Blood Type Diet: dosing

There is no "dose" for the Blood Type Diet — it is an eating pattern, not a pill. Followers are given food lists for their blood type and adjust meals accordingly.If you want to try it, focus on the healthy parts (more whole foods, fewer processed foods) and make sure you still get a full range of nutrients. A pharmacist, doctor, or registered dietitian can help you plan a balanced version and decide whether any supplement, such as a multivitamin, is needed.

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

Read the full Blood Type Diet 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 & Blood Type Diet

Browse every other medication we’ve checked against Blood Type Diet — 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 Blood Type Diet 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 Blood Type Diet list.

See the full Blood Type Diet interactions page

See every supplement checked against Phenylephrine, ranked by severity

Evidence & sources

Blood Type Diet References

The 1 references that drive our Blood Type Diet 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.

Barnard ND, Rembert E, Freeman A, Bradshaw M, Holubkov R, Kahleova H. Blood Type Is Not Associated with Changes in Cardiometabolic Outcomes in Response to a Plant-Based Dietary Intervention. J Acad Nutr Diet. 2020;S2212-2672(20)31197-7. 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

Following Blood Type Diet While Taking Phenylephrine: Common Questions

Is it safe to follow Blood Type Diet while taking Phenylephrine?

We do not list a known interaction between Blood Type Diet 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 — Blood Type Diet 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

Blood Type Diet 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 Blood Type Diet?

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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.