Many people use herbal remedies to supplement their diet. It is always important to do this with caution and to tell your doctor and/or HIV pharmacist what you are taking. Some supplements can stop anti-HIV drugs working properly.

Garlic capsules, which are frequently taken because they are believed to protect the heart, stop the HIV drug saquinavir (Invirase) working properly. Saquinavir is a type of HIV drug called a protease inhibitor and it is thought that garlic capsules could have a similar effect on other protease inhibitors. (Garlic taken in food does not have this effect.)

St John’s wort, the herbal antidepressant, was also shown to be inappropriate for people taking protease inhibitors and another type of HIV drug called NNRTIs (non-nucleoside reverse transcriptase inhibitors). The herb was shown to lower levels of the protease inhibitor indinavir (Crixivan) and researchers concluded that it should not be taken with any other protease inhibitors, NNRTIs or maraviroc (Celsentri), as the body processes all of them in the same way. Commonly prescribed NNRTIs include efavirenz (Sustiva, also in the combination pill Atripla) and nevirapine (Viramune).

Test-tube studies have shown that African potato and Sutherlandia, two herbs sometimes used to treat HIV in Africa, interfere with the body's ability to process protease inhibitors and NNRTIs.

There is also a theoretical risk of an interaction between anti-HIV drugs and many other herbal preparations, including borage oil, DHEA, ginkgo biloba, liquorice, milk thistle and valerian.

Your HIV pharmacist can give specific advice about potential interactions between your anti-HIV drugs and herbal remedies. It is very important that you tell your doctor, pharmacist and dietitian exactly what supplements you are taking or thinking of taking.