Keflex and Headache - a phase IV clinical study of FDA data

Summary:

Headache is reported as a side effect among people who take Keflex (cephalexin), especially for people who are female, 60+ old, have been taking the drug for < 1 month also take Fosamax, and have Rheumatoid arthritis.

The phase IV clinical study analyzes which people have Headache when taking Keflex. It is created by eHealthMe based on reports of 14,902 people who have side effects when taking Keflex from the FDA, and is updated regularly.

What is Keflex?

Keflex has active ingredients of cephalexin. It is often used in infection. eHealthMe is studying from 15,844 Keflex users. Check the latest studies of Keflex.

What is Headache?

Headache (pain in head) is found to be associated with 3,745 drugs and 5,767 conditions by eHealthMe. Check the latest studies of Headache.

On Jul, 05, 2026

14,902 people reported to have side effects when taking Keflex.
Among them, 1,101 people (7.39%) have Headache.

Among these 1,101 people:

* Approximation only. Some reports may have incomplete information.

Do you take Keflex and have Headache?

- Check whether Headache 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 Keflex:

Keflex (15,844 reports)

Headache treatments and more:

Headache (756,642 reports)

How severe was Headache and when was it recovered:

Headache in Keflex

Expand to all the drugs that have ingredients of cephalexin:

Headache and drugs with ingredients of cephalexin (2,693 reports)

Sub-studies by gender and age:

Female: 0-1 2-9 10-19 20-29 30-39 40-49 50-59 60+

Male: 0-1 2-9 10-19 20-29 30-39 40-49 50-59 60+

Browse all side effects of Keflex:

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 Headache:

Headache (3,745 drugs)

Browse all the conditions that are associated with Headache:

Headache (5,767 conditions)

Related publications that referenced our studies

Agrawal A, Rao M, Jasdanwala S, Mathur A, Eng M, "Cephalexin Induced Cholestatic Jaundice", Case reports in gastrointestinal medicine, 2014 Aug .
Agrawal A, Rao M, Jasdanwala S, Mathur A, Eng M, "Cephalexin Induced Cholestatic Jaundice", Case reports in gastrointestinal medicine, 2014 Aug .

How the study uses the data?

The study uses data from the FDA. It is based on cephalexin (the active ingredients of Keflex) and Keflex (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.