The average Ethambutol cash price is about $17.35 for a supply of: Tablet 100 MG 30 pcs. Get our free Ethambutol coupon and be eligible to receive a discount. You can reduce your Ethambutol cost by up to 75% with our free Ethambutol discount card. Bring it to a participating pharmacy near you to save on your prescription medication.Ethambutol is an antibiotic. It prevents growth of the tuberculous bacteria in the body. Ethambutol is used to treat tuberculosis (TB). Ethambutol may also be used for purposes other than those listed in this medication guide.