Overview
Penicillin allergy is an abnormal reaction of the immune system to the antibiotic drug penicillin. It can cause various signs and symptoms, including hives, rash, itching, fever, swelling, shortness of breath, wheezing, runny nose, itchy watery eyes, and in severe cases, anaphylaxis. Anaphylaxis is a life-threatening condition that affects multiple body systems. Penicillin allergy may be over-reported, leading to the use of less-appropriate and more-expensive antibiotic treatments. Accurate diagnosis is important to ensure the best treatment options in the future. Other antibiotics, particularly those with chemical properties similar to penicillin, can also result in allergic reactions.
Understanding the disease
Symptoms
Penicillin allergy symptoms include hives, rash, itching, and severe reactions like anaphylaxis, a life-threatening condition that affects multiple body systems. Other symptoms may include fever, swelling, shortness of breath, wheezing, runny nose, itchy watery eyes, and skin rash. Symptoms often occur within an hour of taking the drug, but they can also appear hours, days, or weeks later. It is essential to see a doctor if you experience any symptoms of penicillin allergy or anaphylaxis, which is a severe allergic reaction.
Risk Factors
Risk factors for developing a penicillin allergy include a history of other allergies, such as food allergy or hay fever; allergic reaction to another drug; a family history of drug allergy; increased exposure to penicillin due to high doses, repetitive use, or prolonged use; and certain illnesses commonly associated with allergic drug reactions, such as infection with HIV or the Epstein-Barr virus.
Development
Penicillin allergy occurs when your immune system becomes hypersensitive to the drug, mistaking it as a harmful substance and reacting as if it were a viral or bacterial infection. Exposure to penicillin at least once is necessary for the immune system to become sensitive to the drug. After the initial exposure, the immune system develops specific antibodies to the drug. The next time penicillin is taken, these antibodies flag the drug and direct immune system attacks on it, causing the signs and symptoms associated with an allergic reaction. Trace amounts of penicillin in the food supply may be sufficient for a person's immune system to create an antibody to the drug.
Assessment and Diagnosis
Triage
When you experience signs or symptoms of penicillin allergy, you should see a doctor as soon as possible. This will help you understand what is an allergic reaction, what is a typical side effect, and what you can tolerate when taking medication. If you suspect a penicillin allergy, it is essential to consult a healthcare professional to determine the best course of action and appropriate treatment options. In case of a severe reaction or suspected anaphylaxis after taking penicillin, call 911 or emergency medical help immediately.
Diagnosis
To diagnose a penicillin allergy, a thorough exam and appropriate diagnostic tests are necessary. Your doctor will conduct a physical examination, ask questions about your symptoms, and order additional tests. These tests may include skin tests, graded challenge, or a combination of both. Skin tests involve administering a small amount of the suspect penicillin to your skin, which can cause a positive reaction if you have an allergy. A positive result indicates a high likelihood of penicillin allergy, while a negative result usually means you are not at high risk of an allergy to penicillin. However, a negative result may not always be accurate, as some types of drug reactions cannot be detected by skin tests. If the diagnosis is uncertain, a graded drug challenge may be recommended. This involves receiving up to five doses of the suspect penicillin, starting with a small dose and increasing to the desired dose. If you reach the therapeutic dose without a reaction, then you are likely not allergic to that type of penicillin. During diagnosis, your doctor will consider factors such as your symptoms, past reactions to drugs, family history of drug allergies, and current medications or supplements you are taking. Providing detailed information about your medical history and any allergies you have can help your doctor make an accurate diagnosis.
Management and Treatment
Complications
Penicillin allergy can lead to several complications, including:
- Serum sickness: This is a delayed allergic reaction that can occur 5 to 14 days after starting penicillin therapy. Symptoms may include fever, joint pain, rash, swelling, and nausea.
- Drug-induced anemia: In rare cases, penicillin can cause a decrease in red blood cells, leading to anemia. Symptoms may include fatigue, irregular heartbeats, shortness of breath, and other related signs.
- Misdiagnosis and inappropriate treatment: Overreporting of penicillin allergies can result in the use of less appropriate and more expensive antibiotic treatments, potentially causing complications due to the incorrect treatment of the underlying infection.
- Delayed reactions: Less common reactions can occur days or weeks after exposure to penicillin and may persist for some time after you stop taking it. These reactions can include serum sickness and drug-induced anemia. It is important to consult with a healthcare professional to accurately diagnose a penicillin allergy and determine the appropriate treatment options to minimize the risk of complications.
Prevention
Although penicillin allergy cannot be completely prevented, there are steps you can take to minimize the risk of developing an allergic reaction to penicillin or other beta-lactam antibiotics. These include:
- Inform health care workers about your allergy: Make sure that your penicillin or other antibiotic allergy is clearly documented in your medical records. Inform other health care professionals, such as your dentist or any medical specialist, about your allergy.
- Wear a medical alert bracelet: Wear a bracelet that identifies your drug allergy. This information can ensure proper treatment in an emergency.
- Avoid penicillin and related drugs: If you have a known penicillin allergy, avoid taking any medications containing penicillin or other beta-lactam antibiotics. Always inform your healthcare provider about your allergy before starting any new medication.
- Monitor your exposure to penicillin: Reduce your exposure to penicillin by avoiding foods containing trace amounts of the drug, such as certain cheeses.
- Consider allergy testing and desensitization: In some cases, your healthcare provider may recommend skin or blood tests to confirm your allergy and, if appropriate, recommend a desensitization process under medical supervision. Remember, it's crucial to discuss your penicillin allergy with your healthcare provider to determine the best course of action for your specific situation.
Treatment
Treating penicillin allergy involves managing symptoms and potentially undergoing drug desensitization. Here's a summary of the treatment options:
- Withdrawal of the drug: If you have a penicillin allergy, the first step is to stop taking the drug.
- Antihistamines: Your doctor may prescribe an antihistamine like diphenhydramine (Benadryl) to help alleviate symptoms.
- Corticosteroids: In more severe cases, oral or injected corticosteroids may be used to reduce inflammation.
- Epinephrine injection: In cases of anaphylaxis, an immediate epinephrine injection is necessary, along with hospital care to maintain blood pressure and support breathing. Drug desensitization may be considered if no other suitable antibiotic options are available. This process involves receiving gradually increasing doses of penicillin under close medical supervision. Remember, it is crucial to consult a healthcare professional for an accurate diagnosis and appropriate treatment plan.