The risk of injection site reactions

Severe responses at the injection site (injection site reactions). Some Vivitrol users have experienced severe injection site reactions, including tissue death (necrosis). Some of these injection site responses have necessitated surgical treatment. A healthcare provider must inject this medicine. If you observe any of the following symptoms at any of your injection locations, contact your healthcare provider right away: severe pain, the area that feels hard, a large area of swelling, lumps, blisters, an open wound, or a dark scab.

Inform your healthcare practitioner if you have any concerns about a reaction at an injection site that gets worse over time or does not improve within two weeks of the injection.