The most common side effect is transient drowsiness, which occurs in the first 2 to 3 days of initiating therapy, or after a dosage increase.

aggravation of angina pectoris, bradycardia (occasional), congestive heart failure, hypertension (rare, following abrupt discontinuation of oral dose), orthostatic hypotension (indicates a need to reduce dosage), prolonged carotid sinus hypersensitivity, sodium and fluid retention (can be controlled with diuretics)

common (occurs early in therapy): asthenia, drowsiness, vertigo, weakness, headache; rare: Bell’s palsy, depression, impaired concentration, involuntary choreoathetoid movements (indicates a need to discontinue methyldopa), memory impairment, nightmares, parasthesia, parkinsonism, reversible mild psychosis

colitis, constipation, diarrhea, distention, dry mouth, flatulence, nausea, sore or black tongue, vomiting

positive Coombs’ test (10-20%), hemolytic anemia (0.1-0.2% of patients who develop a positive Coomb’s test), leukopenia (rare, primarily granulocytopenia), immune thrombocytopenia (rare), bone marrow depression, positive lupus and rheumatoid factor tests, hemolysis in patients with glucose-6-phosphate dehydrogenase deficiency

rare: abnormal liver function tests, cholestatis, jaundice, hepatitis, hepatic necrosis

nasal congestion (common), decreased libido (frequent), impotence (16%), rare: amenorrhea, breast enlargement, gynecomastia, hyperprolactinemia, lactation, increased BUN and serum amylase, blurred vision, nocturia

drug related fever, myocarditis, pericarditis, lupus like syndrome

eczema, hyperkeratosis, lichenoid eruptions, rash, toxic epidermal necrolysis, ulceration of the soles of the feet, urticaria

Table 1: Methyldopa

Established or Predicted Drug-Drug Interactions

Drug Name	Effect	Clinical Comment
Haloperidol	Methyldopa may increase the effects of haloperidol	Use alternative therapy
Iron	Iron may decrease the extent of methyldopa absorption	Use an alternative antihypertensive or give methyldopa 2 hours before or 6 hours after oral iron. Monitor blood pressure
Levodopa	May increase the effect of both levodopa and methyldopa	Monitor blood pressure and signs of levodopa toxicity. Consider using alternative therapy.
Lithium	Methyldopa may increase lithium toxicity	Monitor for lithium toxicity. Consider using an alternative antihypertensive.
MAOI	May cause hallucinations, excitation and severe hypertension	MAOIs are contraindicated with methyldopa therapy
Norepinephrine	Methyldopa may prolong the pressor effects of norepinephrine	monitor for increased blood pressure

Methyldopa tablets can be taken with or without food.