Drug alert: Anti-impotence drug Vegetal Vigra contains drug ingredients which can cause serious side effects.

The Department of Health urges people not to buy or use anti-impotence drug Vegetal Vigra which contains sildenafil and tadalafil which can cause serious side effects.

The department recently found the product on an Internet auction website. It is not a registered pharmaceutical product in Hong Kong.

Both sildenafil and tadalafil are Western medicines usually used for treating male sexual dysfunction. Their side effects include low blood pressure, headache, vomiting, dizziness and transient vision disturbances.

They can interact with nitrates found in some prescription drugs, such as nitroglycerin for treatment of angina, and can lower blood pressure to dangerous levels. Their improper use can pose serious health risks, especially for people with heart problems.

Products containing these ingredients must be registered before sale and can be sold only on a doctor's prescription and under the supervision of a pharmacist.