Valacyclovir hydrochloride and Multiple sclerosis relapse - a phase IV clinical study of FDA data

Summary:

Multiple sclerosis relapse is reported as a side effect among people who take Valacyclovir hydrochloride (valacyclovir hydrochloride), especially for people who are female, 20-29 old, have been taking the drug for < 1 month also take Ranitidine, and have Multiple sclerosis.

The phase IV clinical study analyzes which people have Multiple sclerosis relapse when taking Valacyclovir hydrochloride. It is created by eHealthMe based on reports of 12,770 people who have side effects when taking Valacyclovir hydrochloride from the FDA, and is updated regularly.

What is Valacyclovir hydrochloride?

Valacyclovir hydrochloride has active ingredients of valacyclovir hydrochloride. It is often used in herpes zoster. eHealthMe is studying from 12,929 Valacyclovir hydrochloride users. Check the latest studies of Valacyclovir hydrochloride.

What is Multiple sclerosis relapse?

Multiple sclerosis relapse (reoccurrence of a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath) is found to be associated with 1,030 drugs and 943 conditions by eHealthMe. Check the latest studies of Multiple sclerosis relapse.

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 Aug, 26, 2026

12,770 people reported to have side effects when taking Valacyclovir hydrochloride.
Among them, 77 people (0.6%) have Multiple sclerosis relapse.

Could Valacyclovir hydrochloride cause Multiple sclerosis relapse?

Among these 77 people:

How long have people been on Valacyclovir hydrochloride when they have Multiple sclerosis relapse? *

What is the gender of people who have Multiple sclerosis relapse when taking Valacyclovir hydrochloride? *

female: 90.91 %
male: 9.09 %

What is the age of people who have Multiple sclerosis relapse when taking Valacyclovir hydrochloride? *

What are other drugs people take besides Valacyclovir hydrochloride? *

Ranitidine: 38 people, 49.35%
Methylprednisolone: 34 people, 44.16%
Acetaminophen: 33 people, 42.86%
Baclofen: 33 people, 42.86%
Gabapentin: 33 people, 42.86%
Tylenol: 26 people, 33.77%
Diphenhydramine Hydrochloride: 25 people, 32.47%
Tysabri: 25 people, 32.47%
Prednisone: 21 people, 27.27%
Kesimpta: 14 people, 18.18%

What are other side effects people have besides Multiple sclerosis relapse? *

Headache (pain in head): 46 people, 59.74%
Fatigue (feeling of tiredness): 41 people, 53.25%
Weakness: 40 people, 51.95%
Nausea And Vomiting: 33 people, 42.86%
Dyspnea (difficult or laboured breathing): 33 people, 42.86%
Itching: 32 people, 41.56%
Feeling Abnormal: 32 people, 41.56%
Throat Irritation: 26 people, 33.77%
Pain In Extremity: 25 people, 32.47%
Hot Flush (sudden feelings of heat): 25 people, 32.47%

What are the existing conditions these people have? *

Multiple Sclerosis (a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath): 45 people, 58.44%
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): 30 people, 38.96%
Migraine (headache): 5 people, 6.49%
Flank Pain (a distressing sensation experienced around the lower back and the upper abdomen): 5 people, 6.49%
Oral Candidiasis (fungal infection of mouth): 5 people, 6.49%
Neuralgia (pain in one or more nerves): 5 people, 6.49%
Back Pain: 5 people, 6.49%
Gait Disturbance: 4 people, 5.19%
Nausea (feeling of having an urge to vomit): 2 people, 2.60%
Stress And Anxiety: 2 people, 2.60%

* Approximation only. Some reports may have incomplete information.

Do you take Valacyclovir hydrochloride and have Multiple sclerosis relapse?

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Related studies:

Effectiveness of, long term effects of, and alternative drugs to Valacyclovir hydrochloride:

Valacyclovir hydrochloride (12,929 reports)

Browse all side effects of Valacyclovir hydrochloride:

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 Multiple sclerosis relapse:

Multiple sclerosis relapse (1,030 drugs)

Browse all the conditions that are associated with Multiple sclerosis relapse:

Multiple sclerosis relapse (943 conditions)

How the study uses the data?

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