Valacyclovir and Myositis - a phase IV clinical study of FDA data

Summary:

Myositis is reported as a side effect among people who take Valacyclovir (valacyclovir hydrochloride), especially for people who are male, 40-49 old, also take Posaconazole, and have Chronic lymphocytic leukaemia refractory.

The phase IV clinical study analyzes which people have Myositis 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 42,108 Valacyclovir users. Check the latest studies of Valacyclovir.

What is Myositis?

Myositis (inflammation of the muscles) is found to be associated with 827 drugs and 1,138 conditions by eHealthMe. Check the latest studies of Myositis.

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 Sep, 02, 2026

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

Among these 61 people:

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

female: 13.21 %
male: 86.79 %

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

What are other drugs people take besides Valacyclovir? *

Posaconazole: 35 people, 57.38%
Imbruvica: 26 people, 42.62%
Ibrutinib: 26 people, 42.62%
Cyclophosphamide: 24 people, 39.34%
Dexamethasone: 22 people, 36.07%
Fludarabine Phosphate: 13 people, 21.31%
Nevanac: 10 people, 16.39%
Sulfamethoxazole And Trimethoprim: 10 people, 16.39%
Tylenol: 10 people, 16.39%
Vigamox: 10 people, 16.39%

What are other side effects people have besides Myositis? *

Fever: 36 people, 59.02%
Microsporidia Infection (infection with microsporidia): 35 people, 57.38%
Cardiac Failure Congestive: 35 people, 57.38%
Weakness: 28 people, 45.90%
Pneumonia: 27 people, 44.26%
Device Related Infection: 26 people, 42.62%
Pseudomonas Infection (pseudomonas infection is caused by a bacterium, pseudomonas aeruginosa): 26 people, 42.62%
Lymphopenia (an abnormally low level of lymphocytes in the blood): 26 people, 42.62%
Muscle Aches (muscle pain): 24 people, 39.34%
Polymyositis (inflammatory muscle disease that causes weakness of the skeletal muscles): 24 people, 39.34%

What are the existing conditions these people have? *

Chronic Lymphocytic Leukaemia Refractory (a cancer of blood cells lymphocytes that no longer responds favourably to treatment): 31 people, 50.82%
Chronic Lymphocytic Leukaemia (cancer in which the bone marrow makes too many lymphocytes (a type of white blood cell)): 21 people, 34.43%
Microsporidia Infection (infection with microsporidia): 13 people, 21.31%
Ingrowing Nail: 10 people, 16.39%
Juvenile Rheumatoid Arthritis (joint inflammation in children due to systemic disease): 8 people, 13.11%
Acute Lymphocytic Leukemia (All) (cancer of the white blood cells characterized by excess lymphoblasts): 4 people, 6.56%
Still's Disease Adult Onset (a rare illness that causes high fevers, rash, and joint pain in adult just started): 2 people, 3.28%
Gastrointestinal Stromal Tumor: 2 people, 3.28%
Renal Cell Carcinoma (a kidney cancer): 2 people, 3.28%
Acute Myeloid Leukaemia (acute cancer in which the bone marrow makes abnormal myeloblasts): 2 people, 3.28%

* Approximation only. Some reports may have incomplete information.

Do you take Valacyclovir and have Myositis?

- Check whether Myositis 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 Valacyclovir:

Valacyclovir (42,108 reports)

Myositis treatments and more:

Myositis (13,181 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 Myositis:

Myositis (827 drugs)

Browse all the conditions that are associated with Myositis:

Myositis (1,138 conditions)

Related publications that referenced our studies

Proti? D, Balti? S, Stupar N, Pavlov-Dolijanovi? S, Mugo?a S, Todorovi? Z, "A case of myositis with immunological background associated with statin use", Open Medicine, 2014 Oct .
Proti? D, Balti? S, Stupar N, Pavlov-Dolijanovi? S, Mugo?a S, Todorovi? Z, "A case of myositis with immunological background associated with statin use", Open Medicine, 2014 Oct .

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.