The presence of itchy or painful vesicles on an erythematous base in a dermatomal distribution should be considered Zoster (shingles) until proven otherwise.  Use a Tzanck smear (see Herpes Simplex above) to confirm the diagnosis.  Thoracic segments are the most frequently affected.

The branches of the trigeminal nerve are also frequently involved and can be quite painful.  The ophthalmic branch in particular is quite problematic.  For patients with cranial nerve V¹ involvement, be sure to ask about eye symptoms and do examine the eye.  Keratoconjunctivitis and/or iridocyclitis are potentially serious complications.  Consult with an ophthalmologist.

Treatment of Zoster is threefold in nature:  antiviral medications (if indicated), pain relief, and drying of the vesicles.  Acyclovir 800 mg orally five times a day is helpful only if given with 48 hours of the onset of the rash.  The appropriate doses of valacyclovir and famcyclovir are 1000 mg TID and 500 mg TID respectively.

The pain can be quite severe; prescribe narcotics if required.  The use of Burow's solution to compress the vesicles (see Impetigo above) is soothing and will desiccate the blisters.  

While the vesicular fluid of zoster lesions is minimally contagious, this is usually not a problem in immunocompetent patients.  Patients can return to work with active vesicles as long as the involved area is covered with clothing.

Written and revised by CAPT Dennis A. Vidmar, MC, USN, Department of Military and Emergency Medicine, and Department of Dermatology, Uniformed Services University of the Health Sciences, Bethesda, MD (1999).