Fibromyalgia by David A. Nye, M.D. "Amitriptyline frequently produces mild side effects. An increase in sleepiness or dizziness should be expected when it is first taken. Starting at a low dose taken an hour or more before bedtime and increasing gradually helps minimize these initial side effects. Those patients who notice an initial stimulant effect of amitriptyline, perhaps with a rapid heartbeat, should take it earlier in the evening, so that this effect has given way to sedation by bedtime. By the end of two weeks, most patients are noticing that the side effects are settling down and the medication is beginning to help their fibromyalgia symptoms.
Almost everyone on enough amitriptyline to help fibromyalgia gets a dry mouth and often some constipation. If these side effects are severe, another medication called Mestinon can be added to block them, generally with no other side effects of its own. Amitriptyline may cause a craving for sweets, although usually not for calories in other forms. I recommend you avoid sweets entirely while on amitriptyline to avoid weight gain.
Daily, vigorous exercise is also important in the treatment of fibromyalgia. Exercise is more effective if done in the evening. Fifteen to thirty minutes of exercise is usually sufficient. The exercise seems not to work through conditioning of muscles but rather through a direct, possibly hormonal effect on sleep. Patients who have been exercising regularly and then miss a day usually find that their fibromyalgia symptoms are significantly worse the next day.
The kind of exercise is unimportant as long as it is vigorous. Just make sure to pick something that doesn't increase your pain. The exercise should get your heart rate up and and make you get a little short of breath. Less than vigorous exercise provides no benefit and may actually make you feel worse. Be sure to warm up adequately with some stretches before starting to exercise to avoid injury.
Even with good results from treatment, brief relapses are common, often caused by temporary sleep disturbances, such as staying up as little as one hour late one evening, or skipping exercise. You will do best if you "give in to it" when this happens and try to get extra rest."