Ingredients of drugs like Viagra have been found in medicines being sold in six Chinese herbal shops in NI.
Medicines contained the chemical compounds of impotency drugs
Inspections carried out by the health department found five products containing Sildenafil, one of the main ingredients of Viagra.
The adulterated items had names like Dragon Power and King 100% Natural Male Tonic.
Dr Mike Mawhinney, who carried out the inspections, said anyone concerned should contact their GP or pharmacist.
He said drugs like Viagra "should only be given on prescription".
"The department would advise them to... bring the product along with them, explain that they have taken them, explain that they have learned that they may be adulterated," he said.
"Their GP or pharmacist will know what to do."
Traditional medicines have been used for centuries
At the moment there is nothing to prevent anyone setting up a Chinese medicine shop, so reputable practitioners are calling for the profession to be regulated.
Dr Rifang How, a member of the British Register of Chinese Medicines, said that until there was regulation, patients should check that their practitioner is suitably qualified.
"For patients, it is very essential to go the qualified practitioner and after having a full consultation, get the herbs or products from approved suppliers," she said.
"Patients should be very confident with all the products they have got and confident with the service they have got."
'Element of emotion'
However, Dr Hugh McGavock, a pharmacologist, is against people taking any kind of herbal medicine.
"They are impure, they are unstandardised - you can't be sure of the dosage from one batch to the next, they have multiple plant chemicals in them," he said.
"They are not just pure, natural substances and they mostly have a very, very low.... effectiveness. So you are actually paying to get almost nothing.
"There is a huge element of emotion in this. It's what doctors call the placebo effect. All medicines, if given with enough enthusiasm will do you good, even if there's almost nothing in them.
""My general advice would be if you want magic, go to a magician. If you want medicine go to a doctor or a pharmacist."
BBC Northern Ireland health correspondent Dot Kirby said: "Chinese medicine has been around for 2,000 years.
"Now unscrupulous practitioners are tarnishing its reputation. The regulation of the components of herbal medicines is already tightening.
"Some hope that the regulation of the actual practitioners is not far behind."