Hi Sue, Is your 3x's a week maintenance or normal dosage? My Doctor usually does it daily for 6 months, confirm negative follow-up cultures, then convert to 3 days a week. He also said he increases the Ethambutol dose when going to 3 days. He also mentions that 3 times is for patients with less significant "burden" of MAI. I don't really know what my burden is other than I don't have symptoms and never have. My MAC was found by change with a CT Scan of my abdominal area. Thanks, MACinPA