Tysabri and Clostridium test positive - a phase IV clinical study of FDA data

Summary:

Clostridium test positive is reported as a side effect among people who take Tysabri (natalizumab), especially for people who are female, 60+ old, have been taking the drug for 2 - 5 years also take Ampyra, and have Crohn's disease.

The phase IV clinical study analyzes which people have Clostridium test positive when taking Tysabri. It is created by eHealthMe based on reports of 220,870 people who have side effects when taking Tysabri from the FDA, and is updated regularly.

What is Tysabri?

Tysabri has active ingredients of natalizumab. It is often used in multiple sclerosis. eHealthMe is studying from 221,369 Tysabri users. Check the latest studies of Tysabri.

What is Clostridium test positive?

Clostridium test positive is found to be associated with 297 drugs and 423 conditions by eHealthMe. Check the latest studies of Clostridium test positive.

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, 31, 2026

220,870 people reported to have side effects when taking Tysabri.
Among them, 17 people (0.01%) have Clostridium test positive.

Could Tysabri cause Clostridium test positive?

Among these 17 people:

How long have people been on Tysabri when they have Clostridium test positive? *

What is the gender of people who have Clostridium test positive when taking Tysabri? *

female: 82.35 %
male: 17.65 %

What is the age of people who have Clostridium test positive when taking Tysabri? *

What are other drugs people take besides Tysabri? *

What are other side effects people have besides Clostridium test positive? *

Urinary Tract Infection: 6 people, 35.29%
Wound: 3 people, 17.65%
Mitral Valve Incompetence (inefficient heart valve): 3 people, 17.65%
Crohn's Disease (a condition that causes inflammation of the gastrointestinal tract): 3 people, 17.65%
Pneumonia Pneumococcal (pneumococcal pneumonia is a common but serious infection and inflammation of the lungs): 3 people, 17.65%
Peripheral Arterial Occlusive Disease (reproducible ischemic muscle pain): 3 people, 17.65%
Opportunistic Infection (a microorganism that normally does not cause disease but becomes pathogenic when the body's immune system is impaired and unable to fight): 3 people, 17.65%
Oedema Peripheral (superficial swelling): 3 people, 17.65%
Mobility Decreased (ability to move is reduced): 3 people, 17.65%
Micturition Disorder (disease of passing urine): 3 people, 17.65%

What are the existing conditions these people have? *

Crohn's Disease (a condition that causes inflammation of the gastrointestinal tract): 5 people, 29.41%
Peripheral Arterial Occlusive Disease (reproducible ischemic muscle pain): 2 people, 11.76%
Osteoporosis (bones weak and more likely to break): 2 people, 11.76%
Venous Insufficiency (poor circulation of blood caused by damaged or enlarged veins): 1 person, 5.88%
Insomnia (sleeplessness): 1 person, 5.88%
Coronary Heart Disease (narrowing or blockage of the coronary arteries): 1 person, 5.88%

* Approximation only. Some reports may have incomplete information.

Do you take Tysabri and have Clostridium test positive?

- Check whether Clostridium test positive 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 Tysabri:

Tysabri (221,369 reports)

Browse all side effects of Tysabri:

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 Clostridium test positive:

Clostridium test positive (297 drugs)

Browse all the conditions that are associated with Clostridium test positive:

Clostridium test positive (423 conditions)

How the study uses the data?

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