Subsys and Abnormal behavior - a phase IV clinical study of FDA data

Summary:

Abnormal behavior is reported as a side effect among people who take Subsys (fentanyl), especially for people who are female, 60+ old, have been taking the drug for < 1 month also take Oxycodone, and have Pain.

The phase IV clinical study analyzes which people have Abnormal behavior when taking Subsys. It is created by eHealthMe based on reports of 9,232 people who have side effects when taking Subsys from the FDA, and is updated regularly.

What is Subsys?

Subsys has active ingredients of fentanyl. eHealthMe is studying from 9,239 Subsys users. Check the latest studies of Subsys.

What is Abnormal behavior?

Abnormal behavior is found to be associated with 1,379 drugs and 1,944 conditions by eHealthMe. Check the latest studies of Abnormal behavior.

On Feb, 27, 2026

9,232 people reported to have side effects when taking Subsys.
Among them, 11 people (0.12%) have Abnormal behavior.

Among these 11 people:

* Approximation only. Some reports may have incomplete information.

Do you take Subsys and have Abnormal behavior?

- Check whether Abnormal behavior 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 Subsys:

Subsys (9,239 reports)

Abnormal behavior treatments and more:

Abnormal behavior (51,307 reports)

How severe was Abnormal behavior and when was it recovered:

Abnormal behavior in Subsys

Expand to all the drugs that have ingredients of fentanyl:

Abnormal behavior and drugs with ingredients of fentanyl (467 reports)

Sub-studies by gender and age:

Female: 0-1 2-9 10-19 20-29 30-39 40-49 50-59 60+

Male: 0-1 2-9 10-19 20-29 30-39 40-49 50-59 60+

Browse all side effects of Subsys:

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 Abnormal behavior:

Abnormal behavior (1,379 drugs)

Browse all the conditions that are associated with Abnormal behavior:

Abnormal behavior (1,944 conditions)

How the study uses the data?

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