Some drugs can be stopped abruptly but others may have to be tailed off. Antibiotics should be taken until the course finishes in order to minimise the risk of bacterial resistance to the drug developing. Some people may stop taking the drug as soon as they feel better only to have the symptoms return.

Some people decide to stop taking their treatments because of side-effects. An Italian-British study looked at 862 people who began taking anti-HIV drugs for the first time. Within a year, 21% had stopped treatment due to side-effects whereas only 5% stopped due to treatment failure. Clearly, side-effects are often the reason people stop treatment.

Nevertheless, remember that it is sometimes difficult to tell if you are having an adverse effect from the drug/s or if you are feeling a bit ill due to the wear and tear of life in general or, more specifically, living with HIV. A rule of thumb is that the more drugs you take the higher the chance of having an adverse effect. Rather than suffering in silence with what you feel are adverse effects, or deciding to stop taking the drugs on the spur of the moment, it is a good idea first to discuss the problem with your doctor as it may be possible to prevent or reduce the side-effects.

If you stop a drug such as ritonavir because of side-effects and stay off the drug for more than three weeks, you may find that you will experience the side-effects all over again if you re-start the drug. This is because the side-effects you were experiencing are what is known as induction side-effects, or consequences of abnormally high levels of the drug in your body. As the weeks go on the liver begins to regulate drug levels, and the peaks in drug levels which caused some side-effects will even out. However, if you stop the drug because of the side-effects, the liver will go back to its previous mode of action, and you will face the same process of adjustment (and side effects) all over again.

Bear in mind that some drugs such as anti-depressants can cause adverse effects that are worst when you first start taking them but may then disappear over time. There are some drugs that are designed to help reduce adverse effects, such as prochlorperazine to suppress AZT-induced nausea.

Corticosteroids such as prednisolone or dexamethasone must not be stopped abruptly but must be tailed off to prevent a reaction happening when the treatment is ended. An exception to this is when steroids are given for only one or two doses. You may suffer from withdrawal symptoms if you have been taking opiate drugs such as morphine, pethidine and codeine consistently for several days and then stopped abruptly. The drug should be gradually reduced over a few days.