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

Summary:

Multiple sclerosis is reported as a side effect among people who take Valacyclovir (valacyclovir hydrochloride), especially for people who are female, 40-49 old, have been taking the drug for < 1 month also take Ocrevus, and have Relapsing-remitting multiple sclerosis.

The phase IV clinical study analyzes which people have Multiple sclerosis when taking Valacyclovir. It is created by eHealthMe based on reports of 41,259 people who have side effects when taking Valacyclovir from the FDA, and is updated regularly.

What is Valacyclovir?

Valacyclovir has active ingredients of valacyclovir hydrochloride. It is often used in genital herpes. eHealthMe is studying from 42,106 Valacyclovir users. Check the latest studies of Valacyclovir.

What is Multiple sclerosis?

Multiple sclerosis (a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath) is found to be associated with 1,140 drugs and 1,344 conditions by eHealthMe. Check the latest studies of Multiple sclerosis.

On Sep, 18, 2025

41,259 people reported to have side effects when taking Valacyclovir.
Among them, 61 people (0.15%) have Multiple sclerosis.

Could Valacyclovir cause Multiple sclerosis?

Among these 61 people:

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

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

female: 90 %
male: 10 %

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

What are other drugs people take besides Valacyclovir? *

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

Fatigue (feeling of tiredness): 14 people, 22.95%
Fall: 11 people, 18.03%
Balance Disorder: 10 people, 16.39%
Multiple Sclerosis Relapse (reoccurrence of a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath): 9 people, 14.75%
High Blood Pressure: 7 people, 11.48%
Pain: 7 people, 11.48%
Gait Disturbance: 7 people, 11.48%
Skin Blushing/flushing (a sudden reddening of the face, neck): 7 people, 11.48%
Headache (pain in head): 6 people, 9.84%
Muscle Spasms (muscle contraction): 6 people, 9.84%

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): 11 people, 18.03%
Gait Disturbance: 7 people, 11.48%
Crohn's Disease (a condition that causes inflammation of the gastrointestinal tract): 4 people, 6.56%
Oral Herpes (viral infection of mouth): 3 people, 4.92%
High Blood Pressure: 3 people, 4.92%
Stress And Anxiety: 3 people, 4.92%
Secondary Progressive Multiple Sclerosis (a stage of ms which comes after relapsing remitting ms in many cases): 3 people, 4.92%
Pain: 3 people, 4.92%
Depression: 3 people, 4.92%
Ulcerative Colitis (inflammatory bowel disease (ibd). it causes swelling, ulcerations, and loss of function of the large intestine): 2 people, 3.28%

* Approximation only. Some reports may have incomplete information.

Do you take Valacyclovir and have Multiple sclerosis?

- Check whether Multiple sclerosis is associated with a drug or a condition
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Related studies:

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

Valacyclovir (42,106 reports)

Browse all side effects of Valacyclovir:

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:

Multiple sclerosis (1,140 drugs)

Browse all the conditions that are associated with Multiple sclerosis:

Multiple sclerosis (1,344 conditions)

Drugs similar to Valacyclovir and Multiple sclerosis :

Acyclovir side effect: Multiple sclerosis

Related publications that referenced our studies

Christopher KL, Elner VM, Demirci H, "Conjunctival Lymphoma in a Patient on Fingolimod for Relapsing-Remitting Multiple Sclerosis", Ophthalmic Plastic & Reconstructive Surgery, 2017 May .
Christopher, K. L., Elner, V. M., & Demirci, H. , "Conjunctival lymphoma in a patient on fingolimod for relapsing-remitting multiple sclerosis", Ophthalmic plastic and reconstructive surgery , 2014 Jan .
Christopher KL, Elner VM, Demirci H, "Conjunctival Lymphoma in a Patient on Fingolimod for Relapsing-Remitting Multiple Sclerosis", Ophthalmic Plastic & Reconstructive Surgery, 2017 May .
Christopher, K. L., Elner, V. M., & Demirci, H. , "Conjunctival lymphoma in a patient on fingolimod for relapsing-remitting multiple sclerosis", Ophthalmic plastic and reconstructive surgery , 2014 Jan .

How the study uses the data?

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