About five percent of amoxicillin rashes are true allergies
Dr. Jennie Berkovich
I have a confession: There’s a bottle of amoxicillin in my refrigerator right now, just for backup. I’m notoriously stingy with antibiotics, so having an unnecessary bottle in my fridge feels shameful, but still, sometimes it’s a relief to be able to treat a strep throat or ear infection with the magical pink liquid. However, not a week goes by in my office that I don’t see someone for a suspected amoxicillin allergy.
Amoxicillin rashes come in all shapes and forms and develop up to ten percent of the time. However, the majority are not allergy rashes; the most common cause is actually a drug reaction. This is distinct from an allergy since the mechanism is nonallergic but rather a response to the medication itself. It’s important to make this differentiation — drug rashes from amoxicillin are not dangerous and we do not stop the antibiotic.
These rashes typically appear as small, pink spots or blotches on the skin and typically do not hurt or itch. Drug reaction rashes usually emerge within a few days of starting amoxicillin and often resolve on their own without any complications. Again, as stated above, they do not indicate an allergy to amoxicillin.
Another common cause of a patient on amoxicillin contracting a rash is mono. Mononucleosis, commonly known as mono, is a viral infection caused by the Epstein-Barr virus (EBV). One of the hallmark symptoms of mono is a widespread rash, which can resemble the rash associated with certain drug reactions. Patients with mono are often started on amoxicillin before we know definitively that it’s a virus that is causing the symptoms, and mono patients taking amoxicillin are more likely to develop the mono rash.
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