Benadryl and B-lymphocyte count decreased - a phase IV clinical study of FDA data

Summary:

B-lymphocyte count decreased is reported as a side effect among people who take Benadryl (diphenhydramine hydrochloride), especially for people who are female, 40-49 old, have been taking the drug for < 1 month also take Tylenol, and have Relapsing-remitting multiple sclerosis.

The phase IV clinical study analyzes which people have B-lymphocyte count decreased when taking Benadryl. It is created by eHealthMe based on reports of 100,139 people who have side effects when taking Benadryl from the FDA, and is updated regularly.

What is Benadryl?

Benadryl has active ingredients of diphenhydramine hydrochloride. It is often used in allergies. eHealthMe is studying from 104,954 Benadryl users. Check the latest studies of Benadryl.

What is B-lymphocyte count decreased?

B-lymphocyte count decreased is found to be associated with 126 drugs and 160 conditions by eHealthMe. Check the latest studies of B-lymphocyte count decreased.

On Jul, 16, 2026

100,139 people reported to have side effects when taking Benadryl.
Among them, 25 people (0.02%) have B-lymphocyte count decreased.

Could Benadryl cause B-lymphocyte count decreased?

Among these 25 people:

How long have people been on Benadryl when they have B-lymphocyte count decreased? *

What is the gender of people who have B-lymphocyte count decreased when taking Benadryl? *

female: 81.82 %
male: 18.18 %

What is the age of people who have B-lymphocyte count decreased when taking Benadryl? *

What are other drugs people take besides Benadryl? *

What are other side effects people have besides B-lymphocyte count decreased? *

Multiple Sclerosis (a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath): 7 people, 28.00%
Fatigue (feeling of tiredness): 7 people, 28.00%
Limb Discomfort (discomfort in leg): 6 people, 24.00%
Headache (pain in head): 6 people, 24.00%
Infusion Related Reaction: 5 people, 20.00%
Fever: 5 people, 20.00%
Haemoglobin Decreased: 4 people, 16.00%
Multiple Sclerosis Relapse (reoccurrence of a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath): 4 people, 16.00%
Pharyngitis Streptococcal (inflammation of the pharynx caused by infection from. streptococcus): 4 people, 16.00%
Pneumonia: 4 people, 16.00%

What are the existing conditions these people have? *

Relapsing-Remitting Multiple Sclerosis (reoccurrence of an inflammatory disease in which the insulating covers of nerve cells in the brain and spinal cord are damaged): 12 people, 48.00%
Multiple Sclerosis (a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath): 10 people, 40.00%
Nausea (feeling of having an urge to vomit): 4 people, 16.00%
Migraine (headache): 2 people, 8.00%
Birth Control: 2 people, 8.00%
Depression: 2 people, 8.00%
Dyspnea (difficult or laboured breathing): 2 people, 8.00%
Eye Movements - Uncontrollable: 2 people, 8.00%
Headache (pain in head): 2 people, 8.00%
High Blood Pressure: 2 people, 8.00%

* Approximation only. Some reports may have incomplete information.

Do you take Benadryl and have B-lymphocyte count decreased?

- Check whether B-lymphocyte count decreased 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 Benadryl:

Benadryl (104,954 reports)

Browse all side effects of Benadryl:

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 B-lymphocyte count decreased:

B-lymphocyte count decreased (126 drugs)

Browse all the conditions that are associated with B-lymphocyte count decreased:

B-lymphocyte count decreased (160 conditions)

How the study uses the data?

The study uses data from the FDA. It is based on diphenhydramine hydrochloride (the active ingredients of Benadryl) and Benadryl (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.