Fentanyl 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 Fentanyl (fentanyl citrate), especially for people who are female, 60+ old, have been taking the drug for < 1 month also take Flexeril, and have Epilepsy.

The phase IV clinical study analyzes which people have Red cell distribution width increased when taking Fentanyl. It is created by eHealthMe based on reports of 72,646 people who have side effects when taking Fentanyl from the FDA, and is updated regularly.

What is Fentanyl?

Fentanyl has active ingredients of fentanyl citrate. It is often used in pain. eHealthMe is studying from 73,301 Fentanyl users. Check the latest studies of Fentanyl.

What is Red cell distribution width increased?

Red cell distribution width increased is found to be associated with 608 drugs and 653 conditions by eHealthMe. Check the latest studies of Red cell distribution width increased.

On Jul, 04, 2026

72,646 people reported to have side effects when taking Fentanyl.
Among them, 19 people (0.03%) have Red cell distribution width increased.

Could Fentanyl cause Red cell distribution width increased?

Among these 19 people:

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

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

female: 55.56 %
male: 44.44 %

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

What are other drugs people take besides Fentanyl? *

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

Haemoglobin Decreased: 15 people, 78.95%
Red Blood Cell Count Decreased: 11 people, 57.89%
Haematocrit Decreased: 10 people, 52.63%
Nausea (feeling of having an urge to vomit): 9 people, 47.37%
Platelet Count Increased: 9 people, 47.37%
Weakness: 8 people, 42.11%
Fatigue (feeling of tiredness): 8 people, 42.11%
Mean Cell Volume Decreased (less of the average red blood cell volume): 7 people, 36.84%
Joint Pain: 6 people, 31.58%
Joint Range Of Motion Decreased (disease of joint movement): 6 people, 31.58%

What are the existing conditions these people have? *

Muscle Spasms (muscle contraction): 3 people, 15.79%
Multiple Sclerosis (a nervous system disease that affects your brain and spinal cord. it damages the myelin sheath): 3 people, 15.79%
Epilepsy (common and diverse set of chronic neurological disorders characterized by seizures): 3 people, 15.79%
Cancer Pain: 2 people, 10.53%
Ulcerative Colitis (inflammatory bowel disease (ibd). it causes swelling, ulcerations, and loss of function of the large intestine): 1 person, 5.26%
Sedation: 1 person, 5.26%
Pulmonary Embolism (blockage of the main artery of the lung): 1 person, 5.26%
Peripheral Neuropathy (damage to nerves of the peripheral nervous system): 1 person, 5.26%
Pancreatic Carcinoma (pancreatic cancer): 1 person, 5.26%
Osteoporosis (bones weak and more likely to break): 1 person, 5.26%

* Approximation only. Some reports may have incomplete information.

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

- Check whether Red cell distribution width increased is associated with a drug or a condition
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Related studies:

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

Fentanyl (73,301 reports)

Browse all side effects of Fentanyl:

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 (608 drugs)

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

Red cell distribution width increased (653 conditions)

How the study uses the data?

The study uses data from the FDA. It is based on fentanyl citrate (the active ingredients of Fentanyl) and Fentanyl (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.