A rash is a typical side-effect of this medication, although you may be experiencng hypersensitivity to it. You should contact your physician if it becomes terribly bothersome.
You need to make sure you are wearing gloves when applying this medication.
Where are you applying it by the way?
Also, make sure you use birth control while on this medication. It is a pregnancy risk X which means that it is likely to cause birth defects in a fetus. This precaution is for both men and women while taking the medication.
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Prescription Drug Information, Side Effects, Interactions - Drugs.com