Some pharmacological interactions between herbal preparations and prescribed medication

Posted on September 2, 2017 by admin
In Medical

Reported pharmacological interactions of common herbal preparations with prescription medication from Medical Journal of Australia Feb 2017


St John’s Wort

  • interferes with cyclosporine used to maintain transplants leading to rejection
  • causes intermenstrual bleeding  for women using the oral contraceptive
  • reduces effectiveness of warfarin
  • reduces bioavailability of theophylline , amitriptyline,, methadone, digoxin
  • potentiates side effects of tricyclic and SSRI antidepressants


Asian Ginseng

  • reduces effectiveness of immunosuppressive drugs
  • increases effects of oral hypoglycaemic ( diabetes ) drugs
  • increases side effects of MAOI antidepressants
  • has accumulative effect on benzodiazepines ( Valium, Serepax)



  • increases liver toxicity of paracetamol
  • increases effects of oral hypoglycaemic ( diabetes ) drugs
  • increases incidence of bleeding in users of anticoagulant medication


Evening Primrose  Oil

  • lowers the seizure threshold  for  epileptics
  • interferes with the action of  some anticonvulsants  including phenytoin ( Dilantin)

Dong Quai

  • potentiates   warfarin