Within the recommended dose levels, the following side effects have been reported:
1) Fibrotic Complications
Fibrotic changes have been observed in the retroperitoneal, pleuropulmonary, cardiac, and other tissues, either singly or, very rarely, in combination.
This nonspecific fibrotic process is usually confined to the retroperitoneal connective tissue above the pelvic brim and may present clinically with one or more symptoms such as general malaise, fatigue, weight loss, backache, low grade fever (elevated sedimentation rate), urinary obstruction (girdle or flank pain, dysuria, polyuria, oliguria, elevated BUN), vascular insufficiency of the lower limbs (leg pain, Leriche syndrome, edema of legs, thrombophlebitis). The single most useful diagnostic procedure in suspected cases of retroperitoneal fibrosis is intravenous pyelography. Typical deviation and obstruction of one or both ureters may be observed.
A similar nonspecific fibrotic process, limited to the pleural and immediately subjacent pulmonary tissues, usually presents clinically with dyspnea, tightness and pain in the chest, pleural friction rubs, and pleural effusion. These findings may be confirmed by chest X-ray.
Nonrheumatic fibrotic thickenings of the aortic root and of the aortic and mitral valves usually present clinically with cardiac murmurs and dyspnea.
Other Fibrotic Complications
Several cases of fibrotic plaques, simulating Peyronies Disease have been described.
2) Cardiovascular Complications
Encroachment of retroperitoneal fibrosis on the aorta, inferior vena cava and their common iliac branches may result in vascular insufficiency of the lower limbs, the presenting features of which are mentioned under Retroperitoneal Fibrosis.
Intrinsic vasoconstriction of large and small arteries, involving one or more vessels or merely a segment of a vessel, may occur at any stage of therapy. Depending on the vessel involved, this complication may present with chest pain, abdominal pain, or cold, numb, painful extremities with or without paresthesias and diminished or absent pulses. Progression to ischemic tissue damage has rarely been reported. Prompt withdrawal of the drug at the first signs of impaired circulation is recommended (see WARNINGS) to obviate such effects.
Postural hypotension and tachycardia have also been observed.
3) Gastrointestinal Symptoms
Nausea, vomiting, diarrhea, heartburn, abdominal pain. These effects tend to appear early and can frequently be obviated by gradual introduction of the medication and by administration of the drug with meals. Constipation and elevation of gastric HCl have also been reported.
4) CNS Symptoms
Seizure, insomnia, drowsiness, mild euphoria, dizziness, ataxia, lightheadedness, hyperesthesia, unworldly feelings (described variously as "dissociation", "hallucinatory experiences", etc.). Some of these symptoms may be associated with vascular headaches, per se, and may, therefore, be unrelated to the drug.
5) Dermatological Manifestations
Facial flush, telangiectasia, and nonspecific rashes have rarely been reported. Increased hair loss may occur, but in many instances the tendency has abated despite continued therapy.
Peripheral edema, and, more rarely, localized brawny edema may occur. Dependent edema has responded to lowered doses, salt restriction, or diuretics.
7) Weight Gain
Weight gain may be a reason to caution patients regarding their caloric intake.
8) Hematological Manifestations
Neutropenia, eosinophilia, and thrombocytopenia.
Weakness, arthralgia, myalgia, fever, and mydriasis.
Methysergide may reverse the analgesic activity of narcotic analgesics. Concurrent use with vasoconstrictor agents including ergot alkaloids, sumatriptan, and nicotine (e.g. smoking) may result in enhanced vasoconstriction.