Flexeril and Red cell distribution width increased - a phase IV clinical study of FDA data

Summary:

Red cell distribution width increased is reported as a side effect among people who take Flexeril (cyclobenzaprine hydrochloride), especially for people who are female, 60+ old, have been taking the drug for < 1 month also take Vitamin B12, and have Pain.

The phase IV clinical study analyzes which people have Red cell distribution width increased when taking Flexeril. It is created by eHealthMe based on reports of 34,789 people who have side effects when taking Flexeril from the FDA, and is updated regularly.

What is Flexeril?

Flexeril has active ingredients of cyclobenzaprine hydrochloride. It is often used in muscle spasms. eHealthMe is studying from 38,308 Flexeril users. Check the latest studies of Flexeril.

What is Red cell distribution width increased?

Red cell distribution width increased is found to be associated with 604 drugs and 656 conditions by eHealthMe. Check the latest studies of Red cell distribution width increased.

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, 27, 2026

34,789 people reported to have side effects when taking Flexeril.
Among them, 27 people (0.08%) have Red cell distribution width increased.

Could Flexeril cause Red cell distribution width increased?

Among these 27 people:

How long have people been on Flexeril when they have Red cell distribution width increased? *

What is the gender of people who have Red cell distribution width increased when taking Flexeril? *

female: 65.38 %
male: 34.62 %

What is the age of people who have Red cell distribution width increased when taking Flexeril? *

What are other drugs people take besides Flexeril? *

What are other side effects people have besides Red cell distribution width increased? *

Haemoglobin Decreased: 15 people, 55.56%
Blood Glucose Increased: 14 people, 51.85%
Mean Cell Volume Decreased (less of the average red blood cell volume): 12 people, 44.44%
Haematocrit Decreased: 12 people, 44.44%
Red Blood Cell Count Decreased: 9 people, 33.33%
Weight Decreased: 9 people, 33.33%
Weakness: 8 people, 29.63%
Neutrophil Count Increased (excess than normal number of neutrophil a type of blood cell): 8 people, 29.63%
Mean Cell Haemoglobin Decreased (less than normal haemoglobin per red blood cell in a sample of blood): 8 people, 29.63%
Blood Urea Increased: 8 people, 29.63%

What are the existing conditions these people have? *

Pain: 7 people, 25.93%
Hereditary Neuropathic Amyloidosis (hereditary- diseases resulting from abnormal deposition of certain proteins (amyloid) in various bodily areas by problems with signals from the nerves): 6 people, 22.22%
Osteoarthritis (a joint disease caused by cartilage loss in a joint): 4 people, 14.81%
Rheumatoid Arthritis (a chronic progressive disease causing inflammation in the joints): 3 people, 11.11%
Hepatitis C: 3 people, 11.11%
Multiple Sclerosis (a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath): 3 people, 11.11%
Stress And Anxiety: 3 people, 11.11%
Sleep Disorder: 2 people, 7.41%
Neuropathy Peripheral (surface nerve damage): 2 people, 7.41%
Dyspnea (difficult or laboured breathing): 2 people, 7.41%

* Approximation only. Some reports may have incomplete information.

Do you take Flexeril and have Red cell distribution width increased?

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Related studies:

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

Flexeril (38,308 reports)

Browse all side effects of Flexeril:

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 Red cell distribution width increased:

Red cell distribution width increased (604 drugs)

Browse all the conditions that are associated with Red cell distribution width increased:

Red cell distribution width increased (656 conditions)

How the study uses the data?

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