This Medicines Q&A summarises those drug interactions with tobacco smoking that are considered to be most clinically important.

  • Most interactions between drugs and tobacco smoking are not clinically significant.
  • When giving smoking cessation advice, be aware of a small number of drugs, in particular aminophylline, theophylline, clozapine, erlotinib, olanzapine and riociguat, which may require dose adjustment or increased monitoring when smoking status is altered.
  • Close monitoring of plasma levels (where useful), clinical progress and adverse effect occurrence and severity is essential when patients change their smoking status.
  • Patients taking narrow-therapeutic-index drugs should be monitored closely when any lifestyle modification is made.
  • If the affected drug is prescribed under the supervision of a specialist, their input should be sought if the patient changes their smoking status.