What is one sign of a potential allergic reaction to medication?

A rash or hives is a well-documented sign of a potential allergic reaction to medication. Allergic reactions occur when the immune system reacts abnormally to a substance, which in this case is the medication. The skin can exhibit various symptoms during an allergic response, with rashes and hives being common manifestations. These symptoms often present within minutes to hours after taking the offending medication.

Other signs of an allergic reaction can include swelling, itching, and even more severe symptoms such as difficulty breathing. Recognizing a rash or hives is crucial for timely intervention and management, which may include stopping the medication and providing treatments such as antihistamines or corticosteroids to reduce inflammation and alleviate symptoms.

The other options, while they may indicate other medical issues, are not specific to allergic reactions. Sudden weight gain can be caused by fluid retention or other health issues, temporary memory loss is more commonly associated with neurological factors, and prolonged headaches could be due to a variety of reasons unrelated to allergic responses.