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A drug allergy is an allergic reaction to a drug or medication. An allergic reaction means that your immune system identifies the drug as foreign and acts to eliminate it from your body. Your immune system responds to foreign substances in multiple ways, all of which lead to increased inflammation. These inflammatory responses may cause you to have symptoms such as rash, fever, or breathing difficulties.
Drug allergies are fairly common, especially in children. However, unlike other allergies, drug reactions affect the entire body and can lead to more serious medical conditions.
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Fever, rash, and inflammation are commonly associated with allergies, but if you've recently been exposed to antibiotics they could be symptoms of serum sickness.
If you know that you are allergic to any drug, be sure to inform all of your medical providers, including your dentist and any other care provider who may prescribe medication. It is a good idea to wear a bracelet or necklace or carry a card that identifies your drug allergy—in an emergency, this could save your life. Article Sources:
Penicillin is a common group of antibiotics used to treat a broad range of bacterial infections.
Rash, fever, or inflammation are common drug side effects -- and symptoms of a serious allergic reaction.
Learn more about the types of drug allergies »
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The symptoms of drug allergy may be so mild that you hardly notice them. You might experience nothing more than a slight rash. A severe drug allergy, however, can be life threatening. Anaphylaxis is a sudden, severe, whole-body reaction to a drug or other allergen. It occurs soon after exposure to the substance and includes symptoms such as irregular heartbeat, difficulty breathing, swelling, and unconsciousness. If not treated immediay, anaphylaxis can be fatal.
In some cases, you can be desensitized to a drug. This involves repeated exposure to the drug. Your doctor will start with a very low dose, which will be gradually increased until you develop a tolerance. You should not try to do this on your own. The procedure requires the close supervision of an allergist.
As soon as the drug is identified as a threat, your immune system begins to make antibodies. These are special proteins programmed to attack just that one drug.
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A side effect is any secondary action of a drug. It may be either harmful or beneficial. It is something that might occur in any healthy person taking the drug and does not necessarily involve the immune system.
In some cases, it may be preferable to use the drug that you are known to be allergic to. If this happens, you may be given antihistamines, corticosteroids, or bronchodilators before taking the drug. This should only be done under close medical supervision.
For example, aspirin, which is used to treat headache pain, often causes stomach upset (an adverse side effect) and reduces your chance of heart attack and stroke (a beneficial side effect); acetaminophen (Tylenol), which is used for pain, is associated with liver damage (an adverse side effect); nitroglycerin, which is used to widen blood vessels and improve blood flow, also improves mental function (a beneficial side effect).
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Some drugs, such as morphine, aspirin, some chemotherapy drugs, and the dyes used in some X-rays, can cause an anaphylaxis-type reaction the first time they are used. This does not involve the immune system and is not a true allergy. However, the symptoms and treatment are the same as for true anaphylaxis, and it is just as life threatening.
A drug allergy is a group of symptoms caused by allergic reaction to a drug. An allergic reaction is the result of response by your immune system.
True drug allergy is not common. According to the World Allergy Organization (WAO), it occurs in 3 to 5 percent of hospitalized patients. Additionally, less than 10 percent of adverse drug reactions are caused by genuine drug allergy.
Your immune system can change over time, and it is possible that your allergy will diminish or go away. However, it could also get worse. If you have any symptoms of drug allergy or any side effects to medication you are taking, discuss them with your doctor.
If you have had a previous allergic reaction to a drug, you should avoid using the drug in the future. Your doctor will usually be able to use another drug to treat you.
Learn more about allergies and the immune system »
Learn the difference between allergic reaction and serum sickness »
The immune system helps protect our bodies from bacteria, viruses, and allergens. However, people with chronic allergies may have an overactive immune response that causes itchiness, inflammation, and other potentially serious symptoms.
Mild allergic reactions to drugs can usually be controlled with other medications to block the immune response and reduce symptoms. Such medications may include:
Your immune system is designed to protect you from foreign invaders, such as viruses, bacteria, parasites, and other toxic substances. When a drug enters your body, your immune system may mistake it for one of these invaders. This might happen the first time you take the drug, or it may not be until after you’ve taken it many times with no problems.
Learn more about the causes and symptoms of drug allergies »
Common drug side effects