What is the best course of action for a patient experiencing a worsening rash, possibly due to a reaction to amoxicillin (amoxicillin), on day 9 of treatment for streptococcal (strep) infection, with symptoms including erythema (redness) and pruritus (itching) on the legs, feet, back, and arms, without any signs of anaphylaxis, such as dyspnea (difficulty breathing), wheezing, or facial edema (swelling)?

From the Guidelines

The patient should stop taking amoxicillin immediately as they may have developed an allergic reaction to it, as suggested by the recent study on drug allergy published in the Journal of Allergy and Clinical Immunology in 2022 1. The patient's rash, which started on day 9 of amoxicillin treatment, is likely a delayed hypersensitivity reaction to the antibiotic rather than the original strep infection. Some key points to consider in managing this patient's condition include:

• The patient should pick up and begin using the prescribed cetirizine and hydrocortisone ointment for the rash, as these medications can help alleviate symptoms.
• Until medications are available, cold compresses can help reduce inflammation, and the child should wear loose cotton clothing and stay in a cool room to minimize itching.
• Hot baths and scratching should be avoided, as they can exacerbate the condition.
• If available, Benadryl can be given overnight to help relieve itching and reduce the allergic response.
• It's crucial to keep the child well-hydrated and to monitor for any serious symptoms such as difficulty breathing, facial swelling, or throat tightness, which would require emergency care, as emphasized in the study on drug allergy 1.
• The patient should follow up in clinic first thing in the morning, especially if the rash worsens, to ensure prompt evaluation and management of the condition. This approach prioritizes the patient's safety and well-being, minimizing the risk of a severe allergic reaction while also addressing the symptoms of the rash.

From the FDA Drug Label

5 WARNINGS AND PRECAUTIONS

1. 1 Anaphylactic Reactions Serious and occasionally fatal hypersensitivity (anaphylactic) reactions have been reported in patients on penicillin therapy including amoxicillin. Although anaphylaxis is more frequent following parenteral therapy, it has occurred in patients on oral penicillins These reactions are more likely to occur in individuals with a history of penicillin hypersensitivity and/or a history of sensitivity to multiple allergens. There have been reports of individuals with a history of penicillin hypersensitivity who have experienced severe reactions when treated with cephalosporins Before initiating therapy with amoxicillin, careful inquiry should be made regarding previous hypersensitivity reactions to penicillins, cephalosporins, or other allergens. If an allergic reaction occurs, amoxicillin should be discontinued, and appropriate therapy instituted.
2. 2 Severe Cutaneous Adverse Reactions Amoxicillin may cause severe cutaneous adverse reactions (SCAR), such as Stevens-Johnson syndrome (SJS), toxic epidermal necrolysis (TEN), drug reaction with eosinophilia and systemic symptoms (DRESS), and acute generalized exanthematous pustulosis (AGEP) If patients develop skin rash they should be monitored closely, and amoxicillin discontinued if lesions progress.

The patient's rash could be a sign of an allergic reaction to amoxicillin, which is a known side effect of the medication.

• The FDA drug label warns of anaphylactic reactions and severe cutaneous adverse reactions associated with amoxicillin use.
• Given the patient's symptoms, it is recommended to stop the amoxicillin and monitor the patient closely for any signs of worsening reaction.
• The patient should be advised to seek emergency care if they experience any difficulty breathing, facial swelling, or throat tightness. 2

From the Research

Patient's Condition

• The patient is experiencing a worsening rash, which is very red and spreading, located on her legs, feet, back, and arms.
• The patient was recently diagnosed with strep on 4/14/25 and is on day 9/10 of amoxicillin treatment.
• The onset of the rash was on 4/23/25.
• The patient was prescribed cetirizine and hydrocortisone ointment for her rash, but the medication was not picked up.

Possible Causes of the Rash

• The rash could be due to a reaction to strep or an allergic reaction to amoxicillin, as suggested by the clinic visit with Jennifer Gribble, PA-C 3, 4.
• The patient's symptoms, such as the spreading rash, could be indicative of a non-immediate hypersensitivity reaction to amoxicillin, which is a common antibiotic used to treat strep throat 5.

Treatment and Management

• The patient was advised to stop taking amoxicillin, as it may be causing the allergic reaction.
• The patient was prescribed cetirizine, an antihistamine, to help alleviate the symptoms of the rash, which is a common treatment for allergic reactions 3, 6.
• The patient was also advised to use cold compresses, wear loose cotton clothing, and keep the room cool to reduce itching and inflammation.
• The patient's condition will be monitored, and she will follow up in the clinic in the morning to assess the progression of the rash.

Importance of Proper Diagnosis and Treatment

• Proper diagnosis and treatment of allergic reactions, such as those caused by amoxicillin, are crucial to prevent further complications and ensure the patient's safety 4, 5.
• The use of antihistamines, such as cetirizine, and corticosteroids, such as hydrocortisone, can help alleviate symptoms and prevent further reactions 3, 7.