Many men, including those with HIV/AIDS, can have problems developing and maintaining an erection. Common causes of this can include the following:

cardiovascular diseases
diabetes
less-than-normal levels of testosterone
side effects from medication such as antidepressants
recreational drug use, including alcohol abuse and cigarette smoking
psychological issues such as anxiety, depression and stress
Viagra (sildenafil) is a popular prescription drug for erectile dysfunction. However, Viagra and related drugs—Levitra (vardenafil), Cialis (tadalafil)—can interact with other medications such as protease inhibitors (PIs). Levels of Viagra in the blood increase when the drug is taken by men who are also using PIs. To reduce the risk of side effects from Viagra, such as painful and persistent erections (that last for more than four hours and can damage the penis) and changes to blood pressure and colour vision, Viagra must be used cautiously at lower doses in men who use PIs.

Some men with erectile dysfunction use herbal products marketed for the immediate relief of this condition. Unfortunately, a recent Canadian study has found that two of seven herbal products meant for the treatment of erectile dysfunction were contaminated with the drugs Cialis and Viagra. These contaminants could lead to unexpected side effects, drug interactions and death among unwary users.

Study details
Researchers at hospitals in Toronto and Vancouver bought seven different brands of herbal products, many of which were available for sale over the Internet. The products were in the form of tablets or capsules. These products, their manufacturers claimed, were supposed to improve the quality of erections if taken before sex. None of the herbal products were marketed for daily use.

Samples of these products were analysed in the lab. In two of seven samples, researchers found high levels of Cialis and Viagra. Since these compounds do not occur naturally, the research team concluded that the drugs were deliberately mixed with the herbs.

Although the specific brands of products were not named by the research team, these findings underscore the need for caution when using any "natural" product marketed for the relief of erectile dysfunction. Also, this work supports the efforts of Canada's Natural Health Product's Directorate to regulate and improve the quality of natural health products available to the public.