During acupuncture, patients should not feel pain from the therapy itself. The frequency of treatment will vary according to the particular condition. Treatments last from 5 to 30 minutes, and from 1 to 20 needles may be used. Although some patients experience immediate pain improvement, others require at least 3 treatments. Risks associated with this treatment include fainting, bruising, pain, infection, or injury to underlying tissue, but these reactions are rare. Acupuncture is contraindicated in the treatment of malignancy, mechanical obstruction, fulminant infection, hemorrhagic diseases, or conditions that require surgical repair.