A drug allergy is an abnormal reaction of the immune system to a certain medication. Any medication (over the counter, prescription or herbal) can cause a drug allergy and the most common symptoms include hives, rash or temperature. A drug allergy can cause complications such as allergic reactions, swelling and asthma, which can in turn affect the function of multiple body systems. It is important to note that a drug allergy is not the same as drug side effects. Treatment options for a drug allergy may include injections and certain medications to treat inflammation and relieve symptoms.



Signs and symptoms of a drug allergy may include:

  • Itching of the skin or eyes
  • Skin rash
  • Hives
  • Temperature
  • Swelling
  • Wheezing
  • Runny nose

Anaphylaxis is a rare, life-threatening reaction to a drug allergy that causes widespread dysfunction of body systems. Signs and symptoms of anaphylaxis include:

  • Stomach pain
  • Nausea, vomiting
  • Confusion
  • Diarrhea
  • Dizziness
  • Hives
  • Difficulty breathing
  • Rapid pulse
  • Low blood pressure
  • Seizure
  • Loss of consciousness



Almost any drug can cause an adverse reaction in the immune system. An allergic reaction can occur the first time an individual takes the drug or the second time. A drug allergy occurs when the immune system mistakenly identifies a drug as a harmful substance, as if it were a viral or bacterial infection. The immune system in turn sends out specific antibodies that attack the substance and the chemicals released cause signs and symptoms associated with an allergic reaction.



Possible complications arising from of a drug allergy may include the following:

  • Asthma
  • Life threatening allergic reaction (anaphylaxis)
  • Swelling affecting the throat, tongue and lungs making it difficult to breath
  • Death


Risk factors 

Factors associated with the risk of developing a drug allergy include:

  • An allergic reaction to another drug
  • A family history of drug allergies
  • Increase dose or prolonged use of a certain drug
  • Certain diseases associated with allergic drug reactions (example: HIV infection)




A few recommendations for preventing a drug allergy include:

  • Informing health care workers of medical records to assure proper treatment
  • Wearing a medical bracelet in care of emergency to assure proper treatment
  • Carrying epinephrine autoijectior medication in case of an allergic reaction emergency