55/100 · Moderate
Manufactured by Alkermes, Inc.
Naltrexone Adverse Events: Injection Site Reactions and Nausea Predominate
60,963 FDA adverse event reports analyzed
Last updated: 2026-05-12
NALTREXONE is a medication tracked in the FDA Adverse Event Reporting System (FAERS), manufactured by Alkermes, Inc.. Based on analysis of 60,963 FDA adverse event reports, NALTREXONE has a safety score of 55 out of 100. This moderate score indicates a notable volume of adverse event reports that patients and providers should be aware of. The most commonly reported adverse reactions for NALTREXONE include INJECTION SITE REACTION, INJECTION SITE PAIN, NAUSEA, ALCOHOLISM, INJECTION SITE MASS. This page provides a comprehensive breakdown of reported side effects, safety signals, patient demographics, and AI-powered safety analysis for NALTREXONE.
Naltrexone has a safety concern score of 55 out of 100, placing it in the elevated concern category based on analysis of FDA adverse event data. The FDA has received approximately 60,963 adverse event reports for this medication, which is primarily manufactured by Alkermes, Inc..
The most commonly reported adverse events include Injection Site Reaction, Injection Site Pain, Nausea. Of classified reports, 28.1% were designated as serious by the FDA, meaning they involved hospitalization, disability, or other significant medical outcomes. Injection site reactions, including pain and mass, are the most common adverse events.
Nausea is a frequent side effect, reported by 2094 cases. Serious adverse events, such as death and overdose, are reported but less frequent. Drug dependence and withdrawal syndrome are notable safety concerns.
Patients taking Naltrexone should monitor for the commonly reported side effects and contact their healthcare provider if they experience any unusual symptoms. Naltrexone can cause injection site reactions and may interact with other drugs, leading to potential adverse effects. Always follow the prescribed administration method to minimize risks. This analysis is based on voluntary FDA adverse event reports and should not replace professional medical advice.
Naltrexone received a safety concern score of 55/100 (elevated concern). This is based on a 28.1% serious event ratio across 29,776 classified reports. The score accounts for 60,963 total adverse event reports and 100 distinct reaction types. This elevated score indicates a notable proportion of serious adverse events and warrants careful monitoring.
Adverse event reports by sex: Male: 13,161, Female: 11,958, Unknown: 65. The most frequently reported age groups are age 25 (463 reports), age 37 (431 reports), age 32 (427 reports). These demographics reflect reporting patterns and may not represent the full patient population.
Out of 29,776 classified reports for NALTREXONE:
The FDA classifies an adverse event as “serious” if it results in death, hospitalization, disability, congenital anomaly, or requires intervention to prevent permanent damage.
Demographics reflect voluntary FDA adverse event reporting patterns and may not represent the full patient population.
Naltrexone can cause injection site reactions and may interact with other drugs, leading to potential adverse effects. Always follow the prescribed administration method to minimize risks.
If you are taking Naltrexone, here are important things to know. The most commonly reported side effects include injection site reaction, injection site pain, nausea, alcoholism, injection site mass. While many of these may be mild and temporary, you should contact your healthcare provider if any symptoms are severe or persistent. Follow the prescribed injection method to reduce the risk of injection site reactions. Report any unusual symptoms to your healthcare provider promptly. If you experience a serious adverse reaction, seek emergency medical attention immediately or call 911. You can report side effects to the FDA's MedWatch program at 1-800-FDA-1088.
The FDA continues to monitor naltrexone's safety profile. Healthcare providers should report any adverse events to the FDA's MedWatch program.
The FDA has received approximately 60,963 adverse event reports associated with Naltrexone. These reports come from healthcare professionals, consumers, and manufacturers through the FDA Adverse Event Reporting System (FAERS). Note that the number of reports does not directly indicate the frequency of side effects, as adverse events are voluntarily reported and may be underrepresented.
The most frequently reported adverse events for Naltrexone include Injection Site Reaction, Injection Site Pain, Nausea, Alcoholism, Injection Site Mass. By volume, the top reported reactions are: Injection Site Reaction (4,407 reports), Injection Site Pain (3,110 reports), Nausea (2,094 reports). These figures reflect FDA adverse event reports and may not represent the true incidence rate of these side effects in all patients taking Naltrexone.
Out of 29,776 classified reports, 8,366 (28.1%) were classified as serious and 21,410 as non-serious. The FDA classifies an event as "serious" if it results in death, hospitalization, disability, or other medically significant outcomes. A higher serious-event ratio warrants closer attention but does not necessarily mean the drug is unsafe.
Adverse event reports for Naltrexone break down by patient sex as follows: Male: 13,161, Female: 11,958, Unknown: 65. This distribution reflects reporting patterns rather than actual risk differences between groups. Reporting rates can be influenced by prescribing patterns, disease demographics, and reporting behavior.
The most frequently reported age groups for Naltrexone adverse events are: age 25: 463 reports, age 37: 431 reports, age 32: 427 reports, age 30: 423 reports, age 29: 421 reports. Age-related reporting patterns can reflect both the demographics of the patient population and potential age-related susceptibility to certain side effects.
The primary manufacturer associated with Naltrexone adverse event reports is Alkermes, Inc.. Multiple manufacturers may produce generic versions of this drug. The manufacturer listed reflects the most frequently reported brand in FDA adverse event data.
Beyond the most common reactions, other reported adverse events for Naltrexone include: Fatigue, Pain, Drug Ineffective, Headache, Feeling Abnormal. Less common side effects can still be clinically significant. Patients should report any unusual symptoms to their healthcare provider.
You can report adverse events from Naltrexone to the FDA through their MedWatch program at www.fda.gov/medwatch, by calling 1-800-FDA-1088, or by completing Form FDA 3500. Healthcare professionals, consumers, and manufacturers can all submit reports. Reporting helps the FDA monitor drug safety after approval.
Naltrexone has a safety concern score of 55 out of 100 (elevated concern). This score is calculated from the ratio of serious to non-serious adverse events, the diversity of reported reactions, and the overall volume of reports relative to usage. Injection site reactions, including pain and mass, are the most common adverse events.
Key safety signals identified in Naltrexone's adverse event data include: Injection site reactions (pain, mass, swelling) are the most frequent.. Nausea is a common gastrointestinal side effect.. Serious events like death and overdose are reported but less common.. Drug dependence and withdrawal syndrome are key safety signals.. These signals are derived from patterns in FDA reports and should be discussed with a healthcare provider for personalized assessment.
Naltrexone can cause injection site reactions and may interact with other drugs, leading to potential adverse effects. Always follow the prescribed administration method to minimize risks. Always inform your healthcare provider about all medications, supplements, and over-the-counter drugs you are taking before starting Naltrexone.
Follow the prescribed injection method to reduce the risk of injection site reactions. Report any unusual symptoms to your healthcare provider promptly.
Naltrexone has 60,963 adverse event reports on file with the FDA. Nausea is a frequent side effect, reported by 2094 cases. The volume of reports for Naltrexone reflects both the drug's usage level and the vigilance of the reporting community.
The FDA continues to monitor naltrexone's safety profile. Healthcare providers should report any adverse events to the FDA's MedWatch program. For the most current regulatory information, check the FDA's drug labeling database or consult your pharmacist.
The following drugs share commonly reported adverse reactions with NALTREXONE:
Drugs related to NALTREXONE based on therapeutic use, drug class, or shared indications: