Subacute (DeQuervain's) thyroiditis is a transient inflammatory thyroid disease usually associated with pain and tenderness of the gland, as well as generalized somatic symptoms, which can cause great discomfort or even complete prostration for weeks or months if left untreated. It is almost certainly the result of a viral infection. There is no definitive therapy for painful subacute thyroiditis, but there is effective treatment that will ameliorate the symptoms and allow the disease to run its spontaneous course in an asymptomatic fashion. Salicylates and nonsteroidal antiinflammatory drugs can be used in patients with mild or moderate forms of the disorder. In more severe forms of the condition, corticosteroids in suitable pharmacological dosage will generally cause a rapid relief of symptoms within 24-48 h. Prednisone may be initiated in dosages of 40 mg daily, with a gradual reduction in dosage thereafter over several weeks. Recurrences do appear in a small percentage of patients, necessitating restoration of a higher dose once again. Repeat exacerbations are uncommon. Other less common forms of treatment include triiodothyronine or thyroxine, generally to prevent repeated exacerbations. Irradiation is no longer employed. Thyroidectomy should be considered only in that very small minority of patients who have repeated relapses despite appropriate treatment. During the period of transient hypothyroidism, thyroxine may be provided but can usually be discontinued subsequently. General recovery is almost the universal rule and only less than 1% become permanently hypothyroid.