Sympathomimetics (Direct, Mixed-Acting)/Methyldopa Interactions

This information is generalized and not intended as specific medical advice. Consult your healthcare professional before taking or discontinuing any drug or commencing any course of treatment.

Medical warning:

Moderate. These medicines may cause some risk when taken together. Contact your healthcare professional (e.g. doctor or pharmacist) for more information.

How the interaction occurs:

The cause of the interaction is not known. When these two medicines are taken together, your body may be more sensitive to the blood pressure effects of appetite suppressants, or to medicines used to treat a stuffy nose, cold, or heart condition.

What might happen:

You may experience an increase in blood pressure.

What you should do about this interaction:

Your healthcare professionals (e.g. doctor or pharmacist) may already be aware of this drug interaction and may be monitoring you for it. If your doctor prescribes these two medicines together, you may need to check your blood pressure more often. Do not start, stop, or change the dosage of any medicine before checking with them first.

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  • 2.Dollery CT, Harington M, Hodge JV. Haemodynamic studies with methyldopa: effect on cardiac output and response to pressor amines. Br Heart J 1963; 25(5):670-6.
  • 3.Dollery CT. Physiological and pharmacological interactions of antihypertensive drugs. Proc R Soc Med 1965 Nov;58(11 Part 2):983-7.
  • 4.McLaren EH. Severe hypertension produced by interaction of phenylpropanolamine with methyldopa and oxprenolol. Br Med J 1976 Jul 31; 2(6030):283-4.