Allegra and Rebound effect - a phase IV clinical study of FDA data

Summary:

Rebound effect is reported as a side effect among people who take Allegra (fexofenadine hydrochloride), especially for people who are female, 60+ old, have been taking the drug for 10+ years also take Paxlovid, and have Rosacea.

The phase IV clinical study analyzes which people have Rebound effect when taking Allegra. It is created by eHealthMe based on reports of 73,095 people who have side effects when taking Allegra from the FDA, and is updated regularly.

What is Allegra?

Allegra has active ingredients of fexofenadine hydrochloride. It is often used in allergies. eHealthMe is studying from 75,497 Allegra users. Check the latest studies of Allegra.

What is Rebound effect?

Rebound effect (take-back effect) is found to be associated with 371 drugs and 567 conditions by eHealthMe. Check the latest studies of Rebound effect.

On Jul, 16, 2026

73,095 people reported to have side effects when taking Allegra.
Among them, 20 people (0.03%) have Rebound effect.

Among these 20 people:

How long have people been on Allegra when they have Rebound effect? *

What is the gender of people who have Rebound effect when taking Allegra? *

female: 78.95 %
male: 21.05 %

What is the age of people who have Rebound effect when taking Allegra? *

What are other drugs people take besides Allegra? *

What are other side effects people have besides Rebound effect? *

Headache (pain in head): 3 people, 15.00%
Rashes (redness): 2 people, 10.00%
Rash Macular (small, flat red spots): 2 people, 10.00%
Fatigue (feeling of tiredness): 2 people, 10.00%
Skin Burning Sensation: 2 people, 10.00%
Nausea And Vomiting: 2 people, 10.00%
Pain Of Skin: 2 people, 10.00%
Gait Disturbance: 1 person, 5.00%
Feeling Hot: 1 person, 5.00%
Dyspnea (difficult or laboured breathing): 1 person, 5.00%

What are the existing conditions these people have? *

Rosacea (a skin condition that causes facial redness): 3 people, 15.00%
Multiple Allergies (allergy to multiple agents): 2 people, 10.00%
Hypersensitivity: 2 people, 10.00%
Urticaria (rash of round, red welts on the skin that itch intensely): 1 person, 5.00%
Thyroid Diseases: 1 person, 5.00%
Pollakiuria (abnormally frequent passage of relatively small quantities or urine): 1 person, 5.00%
Muscle Aches (muscle pain): 1 person, 5.00%
Itching: 1 person, 5.00%
Insomnia (sleeplessness): 1 person, 5.00%
Headache (pain in head): 1 person, 5.00%

* Approximation only. Some reports may have incomplete information.

Do you take Allegra and have Rebound effect?

- Check whether Rebound effect 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 Allegra:

Allegra (75,497 reports)

Rebound effect treatments and more:

Rebound effect (8,859 reports)

Browse all side effects of Allegra:

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 Rebound effect:

Rebound effect (371 drugs)

Browse all the conditions that are associated with Rebound effect:

Rebound effect (567 conditions)

How the study uses the data?

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