Drug Allergy

What is Drug Allergy?

When a person develops a drug allergy, their immune system produces an abnormal reaction to a certain medication. It is often unknown that someone is allergic to a substance until after they show a negative reaction to it. Drug allergies are very common, and they are generally more likely to occur in older adults and seniors. They also show up more often in people with a personal or family history of other allergies, those who are frequently exposed to a drug, and when an individual has an illness that makes them more prone to drug allergies. Young children can also develop reactions, but it does not happen quite as often.

Drug allergies are not the same as experiencing the known side effects of medications. They are also very different from drug overdoses and toxicity. Most of the time, allergic reactions are mild and little more than a nuisance. However, in some cases, the allergy is so severe that it can become a life-threatening situation requiring immediate medical intervention.

What are the Symptoms of Drug Allergy?

Some medications are more likely to create an allergic reaction than others.

Symptoms include

  • Rash
  • Hives
  • Fever
  • Nausea
  • Itchiness
  • Swelling
  • Wheezing
  • Watery eyes
  • Runny nose

When symptoms become severe or life threatening, the patient is increasingly likely to experience shock, anaphylaxis, or coma. Without prompt medical attention, such allergic reactions could ultimately lead to death.

Drug Allergy Causes

Drug allergies are caused by the body mistaking chemicals for infectious agents. Histamines are then released which induce the symptoms of drug allergy. Any drug can result in an allergy, but some drugs are much more likely to produce allergic reactions. Particularly, penicillin and similar antibiotics have a tendency to produce allergies. People exposed to those drugs are also exposed to the bacteria used to produce them and this may aggravate symptoms. Another class of drugs often associated with drug allergies are barbiturates. These drugs are processed in such a way that they contain animal byproducts known to induce allergies. A major issue behind drug allergies is improper use. Many antibiotics are used in products commonly sold in supermarkets around the world. When penicillin is injected into beef or used in clothing products, it introduces the antibiotic into the body in an inappropriate way.

How is Drug Allergy Treated?

The easiest way to treat a drug allergy is to avoid the allergen altogether.

Treatment includes

A doctor might direct discontinued use of whatever medication is causing the reaction and prescribe something else in its place. If that cannot be done, and if symptoms are mild, other medicines like antihistamines or steroids can reduce allergic reactions. Drug desensitization may also be used to see if the allergy can be remedied. Patients with more severe reactions may require epinephrine or bronchodilators.

Drug Allergy Prevention

Unlike other allergies, exposure itself is not the best solution to a drug allergy. Unnecessary use of drugs can produce tolerance or cause pathogens to develop immunity to them. The solution to drug allergies is to remove products that might introduce them as something other than a drug. For instance, one should avoid consuming food which is likely to be contaminated with antibiotics. This isn’t always easy, but prepackaged foods tend to have more antibiotics than others.

Another important step in keeping drug allergy away is making sure you take medication as instructed by a doctor. Taking medication less often or more often than necessary will open up the potential to have an allergy. If you have an allergy to an existing animal byproduct that may be used in the drugs you are prescribed, the doctor should be informed of their existence in order to prevent the development of a drug allergy.

Last Reviewed:
September 20, 2016
Last Updated:
December 15, 2017