Hailey Hailey and Darier disease are rare genetic dermatoses. Mutations of 2 genes (ATP2C1 or ATP2A2 respectively) are responsible for the diseases. These genes have a key role in calcium pump; their defect create abnormal link between keratinocytes' desmosomes and induce skin lesions. Clinically, patients present with inflammatory lesions located in the folds. Quality of life is impaired because of pain, pruritus and tendency to infections. Lesions are permanent but acute exacerbations occur in hot seasons because of increased sweating. Usual therapies are often not effective (local treatment, laser, phototherapy). Because sweating is a well established inducing or aggravating factor, botulism toxin could be an effective treatment for these diseases.