Pityriasis rosea-like eruption associated with ondansetron use in pregnancy.

A 30-year-old pregnant female presented with a 2-week history of pityriasis rosea-like eruption. The rash started 2 days after the patient had started taking ondansetron 8 mg for alleviation of moderate-to-severe nausea and vomiting of pregnancy. Physical examination revealed erythematous papulosquamous lesions characterized by annular scaly margins and a dusky centre over the arms, chest, abdomen, lower back and legs. The rash did not involve the palms, sole or mucous membranes, and no lesions were observed on the lymph nodes. Ondansetron was discontinued. The rash ceased to spread and started to disappear within 2 weeks with full resolution noted after 1 month. Analysis of the case using the Naranjo adverse drug reaction probability scale indicated that ondansetron was the probable cause of the pityriasis rosea-like eruption. This is the first case report of pityriasis rosea related to ondansetron therapy.