Medsafe is warning that impotence drugs sold via the internet and in sex shops could be fatal to people with heart conditions.
The Medicines Safety Authority says although many of the drugs are labelled 'herbal', it believes some may contain sildenafil, the active ingredient in Viagra and similar medications.
Medsafe's spokesperson, Derek Fitzgerald, says sildenafil can be fatal if mixed with some heart medications.
Mr Fitzgerald says Medsafe is not aware of any deaths caused by the drugs in this country.
It is asking people to contact them if they see shops or websites selling the drugs and to not take any they may have already purchased.
Medsafe says those who continue to sell unapproved impotence medicines could be fined up to $100,000.