Famvir and White blood cell count decreased - a phase IV clinical study of FDA data

Summary:

White blood cell count decreased is reported as a side effect among people who take Famvir (famciclovir), especially for people who are female, 60+ old, have been taking the drug for < 1 month also take Benadryl, and have Multiple myeloma.

The phase IV clinical study analyzes which people have White blood cell count decreased when taking Famvir. It is created by eHealthMe based on reports of 2,955 people who have side effects when taking Famvir from the FDA, and is updated regularly.

What is Famvir?

Famvir has active ingredients of famciclovir. It is often used in herpes labialis (oral herpes simplex). eHealthMe is studying from 3,061 Famvir users. Check the latest studies of Famvir.

What is White blood cell count decreased?

White blood cell count decreased is found to be associated with 2,076 drugs and 3,076 conditions by eHealthMe. Check the latest studies of White blood cell count decreased.

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, 01, 2026

2,955 people reported to have side effects when taking Famvir.
Among them, 70 people (2.37%) have White blood cell count decreased.

Could Famvir cause White blood cell count decreased?

Among these 70 people:

How long have people been on Famvir when they have White blood cell count decreased? *

What is the gender of people who have White blood cell count decreased when taking Famvir? *

female: 60 %
male: 40 %

What is the age of people who have White blood cell count decreased when taking Famvir? *

What are other drugs people take besides Famvir? *

What are other side effects people have besides White blood cell count decreased? *

Thrombocytopenia (decrease of platelets in blood): 35 people, 50.00%
Fever: 23 people, 32.86%
Haemoglobin Decreased: 22 people, 31.43%
Haematocrit Decreased: 16 people, 22.86%
Nausea (feeling of having an urge to vomit): 15 people, 21.43%
Diarrhea: 13 people, 18.57%
Neutrophil Count Decreased (less than normal number of neutrophil a type of blood cell): 12 people, 17.14%
Anaemia (lack of blood): 11 people, 15.71%
Fatigue (feeling of tiredness): 11 people, 15.71%
Febrile Neutropenia (fever with reduced white blood cells): 10 people, 14.29%

What are the existing conditions these people have? *

Multiple Myeloma (cancer of the plasma cells): 14 people, 20.00%
T-Cell Prolymphocytic Leukaemia (a aggressive type of t cell cancer): 5 people, 7.14%
Urination - Excessive Volume: 4 people, 5.71%
Myelodysplastic Syndrome (a group of conditions that occur when the blood-forming cells in the bone marrow are damaged): 4 people, 5.71%
Nausea (feeling of having an urge to vomit): 4 people, 5.71%
Polycythaemia Vera (blood disorder in which the bone marrow makes too many red blood cells): 3 people, 4.29%
Insomnia (sleeplessness): 3 people, 4.29%
Muscle Spasms (muscle contraction): 3 people, 4.29%
Herpes Simplex (herpes simplex is a common viral infection): 3 people, 4.29%
Acute Myeloid Leukaemia (acute cancer in which the bone marrow makes abnormal myeloblasts): 3 people, 4.29%

* Approximation only. Some reports may have incomplete information.

Do you take Famvir and have White blood cell count decreased?

- Check whether White blood cell count decreased 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 Famvir:

Famvir (3,061 reports)

Browse all side effects of Famvir:

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 White blood cell count decreased:

White blood cell count decreased (2,076 drugs)

Browse all the conditions that are associated with White blood cell count decreased:

White blood cell count decreased (3,076 conditions)

How the study uses the data?

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