Interactions

Medicines can interact, or interfere with the way other medicines work.

This can mean that you don't have enough of a drug present in your blood for it to work properly. If this happens with anti-HIV drugs, it can risk the development of resistance.

Or it can mean that you have too much of a drug and this can mean that there's more of a chance of side-effects developing.

Interactions are one of the reasons why it makes very good sense for your HIV doctor (and any other medical professional who prescribes you medicines) to know about all the medicines and drugs you are taking.

There are interactions between some anti-HIV drugs and everyday, over-the-counter medicines that it’s important to be aware of. It always makes good sense to read the leaflet that comes with all medicines as this will include information about possible drug interactions.

Antacids

Some anti-HIV drugs can interact with antacid medicines. This is a particularly the case with atazanavir (Reyataz), but might also be the case with other protease inhibitors as well.

The research isn’t conclusive, but there is concern that antacid medicines that are in proton pump inhibitor class, such as omeprazole (Losec) or are histamine-2 blockers, for example  ranitidine (Zantac) might lower levels of atazanavir.

If you need to take indigestion remedies and are taking a protease inhibitor it makes good sense to speak to a member of your HIV healthcare team about your options.

It’s important to know that you’re recommended to leave at least ten hours between taking a dose of antacid medicines like Zantac and taking your atazanavir.

Antihistamines

Some anti-HIV drugs can also interact with some types of antihistamines – types of medicines that are taken for hay fever and allergies.

It makes good sense to speak to a member of your HIV team if you regularly need to take antihistamines. Your doctor may be able to prescribe you some that are safe to take with your anti-HIV drugs.

Protease inhibitors and NNRTIs are the types of anti-HIV drug most likely to interact with antihistamines. If you are buying them over the counter from a chemist, then it’s good to know that antihistamines that contain cetirizine don’t interact with anti-HIV drugs.

There’s a risk of an interaction between anti-HIV drugs and antihistamines that contain fexofenadine and loratadine.

You should not take antihistamines that contain astemizole or terfenadine if you are taking HIV treatment.  

Cold and flu remedies

Cold and flu remedies contain painkillers, normally paracetamol. There is no interaction between paracetamol and anti-HIV drugs, but it’s important to know that paracetamol should be used carefully if you have any liver problems.