Insect bite hypersensitivity (IBH) is the most common cause of pruritus in horses and is a serious welfare issue for affected animals. In this study, the effect of a topical phytogenic ointment on the healing of cutaneous lesions was investigated in a double-blind trial involving 26 horses with I B H. The number of lesions and their total surface area were recorded on days 0, 7, and 21 in horses treated for 3 weeks with either verum or placebo ointment. After unblinding of treatment assignment, the horses that had been treated with the placebo ointment received the verum preparation for an additional 3 weeks and the number of lesions and their total surface area were again recorded. This part of the study was not blinded. The number of lesions and the total surface area decreased in both treatment groups (no significant difference). Owners also scored the degree of discomfort suffered by their horses as a result of IBH lesions, and at the end of the 3-week period this score was significantly lower in the verum than in the placebo group (P = 0.04). When placebo-treated horses subsequently received the verum ointment, their wound severity score also decreased significantly (P < 0.01). Daily application of an ointment (verum or placebo) does not cure IBH, but use of the phytogenic ointment led to a decrease in the owner-assessed discomfort suffered by horses.