Diphen and Type iv hypersensitivity reaction - a phase IV clinical study of FDA data

Summary:

Type iv hypersensitivity reaction is reported as a side effect among people who take Diphen (diphenhydramine hydrochloride), especially for people who are female, 60+ old, have been taking the drug for < 1 month also take Prednisone, and have Crohn's disease.

The phase IV clinical study analyzes which people have Type iv hypersensitivity reaction when taking Diphen. It is created by eHealthMe based on reports of 113,958 people who have side effects when taking Diphen from the FDA, and is updated regularly.

What is Diphen?

Diphen has active ingredients of diphenhydramine hydrochloride. It is often used in insomnia. eHealthMe is studying from 115,432 Diphen users. Check the latest studies of Diphen.

What is Type iv hypersensitivity reaction?

Type iv hypersensitivity reaction (delayed type hypersensitivity as the reaction takes two to three days to develop) is found to be associated with 193 drugs and 415 conditions by eHealthMe. Check the latest studies of Type iv hypersensitivity reaction.

eHealthMe: drug outcomes in the real world

eHealthMe runs one of the largest post-marketing drug safety studies in the world. We study millions of patients and 5,000 more each day. Our data-driven phase IV clinical trials have been referenced on 800+ peer-reviewed medical publications including The Lancet, Mayo Clinic Proceedings, and Nature. Tools to study our phase IV findings are available to the public, anonymous and free >>>.

On Sep, 02, 2026

113,958 people reported to have side effects when taking Diphen.
Among them, 14 people (0.01%) have Type iv hypersensitivity reaction.

Could Diphen cause Type iv hypersensitivity reaction?

Among these 14 people:

How long have people been on Diphen when they have Type iv hypersensitivity reaction? *

What is the gender of people who have Type iv hypersensitivity reaction when taking Diphen? *

female: 58.33 %
male: 41.67 %

What is the age of people who have Type iv hypersensitivity reaction when taking Diphen? *

What are other drugs people take besides Diphen? *

What are other side effects people have besides Type iv hypersensitivity reaction? *

Drug Ineffective: 2 people, 14.29%
Red Man Syndrome (a reaction to the drug vancomycin): 2 people, 14.29%
Rash Follicular (redness of hair follicle): 2 people, 14.29%
Paraesthesia (sensation of tingling, tickling, prickling, pricking, or burning of a person's skin with no apparent long-term physical effect): 2 people, 14.29%
Weakness: 1 person, 7.14%
Infective Pulmonary Exacerbation Of Cystic Fibrosis (severe infective lung disease with production of abnormally thick mucus): 1 person, 7.14%
Infection: 1 person, 7.14%
Indigestion: 1 person, 7.14%
Hypophagia (reduced food intake): 1 person, 7.14%
High Blood Pressure: 1 person, 7.14%

What are the existing conditions these people have? *

Fabry's Disease (build up of a particular type of fat, called globotriaosylceramide, in the body's cells): 2 people, 14.29%
Crohn's Disease (a condition that causes inflammation of the gastrointestinal tract): 2 people, 14.29%
Rickets (softening of bones): 1 person, 7.14%
Anaphylaxis (serious allergic reaction that is rapid in onset and may cause death): 1 person, 7.14%
Chickenpox (infection with varicella zoster virus): 1 person, 7.14%
Conjunctivitis (pink eye): 1 person, 7.14%
Constipation: 1 person, 7.14%
Cystic Fibrosis (disease of the secretary glands): 1 person, 7.14%
Dehydration (dryness resulting from the removal of water): 1 person, 7.14%
Enlarged Prostate: 1 person, 7.14%

* Approximation only. Some reports may have incomplete information.

Do you take Diphen and have Type iv hypersensitivity reaction?

- Check whether Type iv hypersensitivity reaction is associated with a drug or a condition
- Predict drug outcomes for up to one year with AI
- Get an AI agent to monitor your drugs continuously

Related studies:

Effectiveness of, long term effects of, and alternative drugs to Diphen:

Diphen (115,432 reports)

Browse all side effects of Diphen:

a b c d e f g h i j k l m n o p q r s t u v w x y z

Browse all the drugs that are associated with Type iv hypersensitivity reaction:

Type iv hypersensitivity reaction (193 drugs)

Browse all the conditions that are associated with Type iv hypersensitivity reaction:

Type iv hypersensitivity reaction (415 conditions)

How the study uses the data?

The study uses data from the FDA. It is based on diphenhydramine hydrochloride (the active ingredients of Diphen) and Diphen (the brand name). Other drugs that have the same active ingredients (e.g. generic drugs) are not considered. Dosage of drugs is not considered in the study.

How to use the study?

DO NOT STOP MEDICATIONS without first consulting your doctor. If there are any serious or long term adverse effects discovered in the study, discuss the study with your doctor to ensure that proper medication management will be in place if applicable.

Who is eHealthMe?

With medical big data and proven AI/ML algorithms, eHealthMe provides a platform for everyone to run phase IV clinical trials. We study millions of patients and 5,000 more each day. Results of our real-world drug study have been referenced on 800+ peer-reviewed medical publications, including The Lancet, Mayo Clinic Proceedings, and Nature. Our analysis results are available to researchers, health care professionals, patients (testimonials), and software developers (open API).

WARNING, DISCLAIMER, USE FOR PUBLICATION

WARNING: Please DO NOT STOP MEDICATIONS without first consulting a physician since doing so could be hazardous to your health.

DISCLAIMER: All material available on eHealthMe.com is for informational purposes only, and is not a substitute for medical advice, diagnosis, or treatment provided by a qualified healthcare provider. All information is observation-only. Our phase IV clinical studies alone cannot establish cause-effect relationship. Different individuals may respond to medication in different ways. Every effort has been made to ensure that all information is accurate, up-to-date, and complete, but no guarantee is made to that effect. The use of the eHealthMe site and its content is at your own risk.

If you use this eHealthMe study on publication, please acknowledge it with a citation: study title, URL, accessed date.