What do I do if I see a scratch on my arm and it swells up and the surrounding area reddens, is it serious?

No, it is not serious. This kind of skin reaction, if associated with itching, is likely to be allergic. If associated with pain or burning sensation, it is likely to be an abrasive scratch. Both these conditions can be managed easily with topical ointments and rarely need any oral medication. In some cases, it may be self limiting. So relax, and consult your family doctor for further advise, if required.

Compass Urgent Care