Reviewed on 6/6/2023

What Is Methyldopa and How Does It Work?

Methyldopa is a prescription medication used to treat the symptoms of Hypertension, Hypertensive Crisis. 

  • Methyldopa is available under the following different brand names: Aldomet

What Are Dosages of Methyldopa?

Adult and Pediatric dosage

Injectable solution

  • 50 mg/mL


  • 250mg
  • 500mg


Adult dosage

  • Initial: 250 mg orally every 8-12 hours for 2 days, increase every 2 days as needed
  • Maintenance: 250-1000 mg/day divided every 6-12 hours orally, usually no more than 3 g/day
  • IV (methyldopate): 250-1000 mg infusion over 30-60 minutes every 6-8 hours as needed, no more than 4 g/day

Pediatric dosage

  • Neonate: 2.5-5 mg/kg orally or IV every 8 hours
  • 10 mg/kg/day divided every 12 hours orally, increase every 2 days as needed

Hypertensive Crisis

Adult dosage

  • 20-40 mg/kg/day divided IV every 6 hours
  • No more than 65 mg/kg/day or 3 g/day (whichever is less)

Pediatric dosage

  • 20-40 mg/kg/day IV divided every 6 hours
  • No more than 65 mg/kg/day or 3 g/day (whichever is less)

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”.

What Are Side Effects Associated with Using Methyldopa?

Common side effects of Methyldopa include:

  • drowsiness, 
  • weakness, and 
  • headache

Serious side effects of Methyldopa include:

  • hives, 
  • difficulty breathing, 
  • swelling of the face, lips, tongue, or throat, 
  • lightheadedness
  • pale or yellowed skin, 
  • dark colored urine, 
  • fever, 
  • confusion, 
  • weakness, 
  • uncontrolled or involuntary muscle movements, 
  • swelling, 
  • rapid weight gain, 
  • shortness of breath, 
  • loss of appetite, 
  • upper stomach pain (that may spread to the back), 
  • nausea, 
  • vomiting, 
  • fast heart rate, 
  • dark urine, and
  • yellowing of the skin or eyes

Rare side effects of Methyldopa include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Methyldopa?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them.  Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider or pharmacist first

  • Methyldopa has severe interactions with no other drugs.
  • Methyldopa has serious interactions with at least 29 other drugs.
  • Methyldopa has moderate interactions with at least 52 other drugs.
  • Methyldopa has minor interactions with the following drugs:

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drugs interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use.  Keep a list of all your medications with you, and share this information with your doctor and pharmacist.  Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Methyldopa?


  • Active liver disease, liver disorders associated with previous methyldopa treatment
  • Hypersensitivity to methyldopa or other ingredients (eg, sulfites)
  • Pheochromocytoma
  • Concomitant MAOIs

Effects of drug abuse

  • None

Short-Term Effects

  • See “What are Side Effects Associated with Using Methyldopa?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Methyldopa?”


  • CHF, dialysis patients (increased risk of hypertension following procedure), edema, hemolytic anemia, hypotension, severe bilateral CVD, history of liver disease
  • Avoid abrupt withdrawal
  • Risk of decreased libido and impotence in men
  • May impair ability to perform hazardous tasks
  • Tolerance develops on prolonged treatment, especially if no concurrent diuretic (methyldopa causes Na and water retention)
  • Interferes with some lab tests
  • IM/SC NOT recommended due to erratic absorption

Pregnancy and Lactation

  • Use may be acceptable during pregnancy.
  • Distributed in breast milk but not in clinically significant amounts; compatible with breastfeeding.

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