interaction with drugs

Last reviewed 01/2018

MAOIs must not be used to treat a patient if the patient is also taking drugs that depend on enzymes affected by MAOI for their metabolism, for example:-

  • sympathomimetic amines eg adrenaline, noradrenaline
  • cold cures containing phenylpropanolamine and ephedrine
  • methyl dopa
  • antihistamines
  • some local anaesthetics
  • morphine, pethidine, procaine, alcohol, insulin, barbiturates. The effects of oral hypoglycaemic drugs may be heightened.

There may be dangerous interactions between tricyclics and MAOIs, which means that a tricyclic should not be given for about 2 weeks after stopping a MAOI. A drug- free interval is not required if the tricyclic is given first, which is a reason why tricyclics are used first in depressive illness and having a MAOI as a reserve.