From the Guidelines
To treat a penicillin rash, first stop taking the penicillin medication immediately and contact your healthcare provider. For mild symptoms, take an antihistamine like diphenhydramine (Benadryl) 25-50mg every 6 hours or cetirizine (Zyrtec) 10mg daily to reduce itching, as seen in studies where cutaneous-only manifestations were successfully treated 1. Apply calamine lotion or 1% hydrocortisone cream to affected areas 2-3 times daily to soothe the skin. Cool compresses and lukewarm oatmeal baths can also provide relief. Avoid scratching to prevent infection. Drink plenty of fluids and rest while your body recovers. The rash typically resolves within 1-2 weeks after stopping the medication.
Some key points to consider when treating a penicillin rash include:
- The prevalence of penicillin allergy labels is higher in individuals who actively use healthcare, in females, in hospitalized patients, and increases with age 1
- Allergic reactions can be immediate, accelerated, or late, and can range from mild to severe, including anaphylaxis and Stevens-Johnson syndrome 1
- Testing for penicillin allergy could be an approach to optimize antibiotic selection and improve patient safety by preventing allergic reactions 1
- Removing incorrect penicillin allergy labels (i.e., penicillin allergy delabeling) is of importance to improve antimicrobial stewardship practices worldwide 1
For severe reactions including difficulty breathing, facial swelling, or blistering rash, seek emergency medical attention immediately as these could indicate anaphylaxis or Stevens-Johnson syndrome. After recovery, ask your doctor about allergy testing to confirm a penicillin allergy, as this will affect future antibiotic choices. Penicillin rashes occur because your immune system mistakenly identifies the drug as harmful and releases histamine, causing inflammation and skin symptoms.
From the Research
Treatment of Penicillin Rash
- The treatment of penicillin rash depends on the type and severity of the reaction 2
- For mild reactions, such as hives or pruritic rashes, antihistamines may be used 2
- For more severe reactions, such as anaphylaxis, epinephrine and glucocorticoids may be necessary 3, 2
- In some cases, desensitization may be used to allow for the continued use of penicillins 2
Assessment of Penicillin Allergy
- A thorough assessment of the patient's medical history is necessary to determine the risk of a penicillin allergy 4, 5
- Patients with a low-risk history, such as isolated non-allergic symptoms or a family history of penicillin allergy, may be suitable for an oral rechallenge with low-dose penicillin 4, 5
- Penicillin skin testing may be used to evaluate patients with a moderate-risk history, and has a negative predictive value of over 95% 4
- Patients with a high-risk history, such as anaphylaxis or positive penicillin skin testing, should avoid penicillins and other beta-lactam antibiotics 4
Management of Penicillin Allergy
- The goals of antimicrobial stewardship are undermined when reported allergy to penicillin leads to the use of broad-spectrum antibiotics 4
- Evaluation of penicillin allergy before deciding not to use penicillin or other beta-lactam antibiotics is an important tool for antimicrobial stewardship 4
- In many cases, with appropriate assessment and allergy testing, it may be possible to remove the penicillin allergy label 5
- Patients who have survived an anaphylactic reaction should be thoroughly examined and an allergy diagnosis should be performed with regard to the eliciting agent and the pathogenic mechanism involved 3