A reader wrote recently to ask, "My Synthroid isn't working! What should I do?" She had started Synthroid three or four weeks earlier, and was still exhausted and gaining weight. So her first thought was that the Synthroid wasn't working. It's actually a common question. Patients think that the medication isn't working if after a few weeks, they still have troublesome symptoms. But if this happens to you, does this mean your medication -- and Synthroid is the brand name levothyroxine drug most often prescribed for thyroid patients -- really isn't working? Not necessarily. Before you make any assumptions, explore the following questions...