Symptoms of a drug allergy usually develop within a hour of ingesting the drug.

Symptoms of a mild drug allergy include:

• Increased sensitivity to sunlight
• Erythema multiforme
• Hives:
• Rash in children
• Rash in adults
• Eye redness
• Itching
• Nasal congestion
• Runny nose

Symptoms of a severe drug allergy include:

• Chest pain
• Difficulty breathing
• Facial swelling
• Fainting
• Low blood pressure
• Mouth or throat swelling
• Rapid pulse
• Severe hives
• Severe wheezing
• Vomiting