Side-effects soon after starting treatment

Most side-effects occur after you have been taking a medicine for a week or two. However, there is no strict pattern, and some people develop side-effects after taking their first dose of a drug. For others, side-effects don’t develop for many months.

Side-effects occur in the first month or so of taking a drug not because you are being poisoned by the medicine, but because you have especially high concentrations of a drug in your blood in the weeks and months after you first start taking it. Over time, the peak drug levels in your blood go down, and side-effects tend to wear off. Because of this, it might be recommended in some cases that you gradually increase the dose of a drug you take over a few weeks.

Side-effects are often worse during the first month or so of taking a drug. Over time, they may lessen, modify, or go away altogether.

Daily pattern to side-effects

There can be a daily pattern to side-effects, linked to the time you take your medicines and also to the processing of the drug by your body. It might be possible to minimise the inconvenience that this causes by taking your medicines at certain times. For example, the non-nucleoside reverse transcriptase inhibitor (NNRTI) efavirenz (Sustiva) can cause dizziness and other psychological side-effects. Many people overcome these by taking their daily dose of the drug just before going to bed.

Medicines to control short-term side-effects

Medicines are available to help control side-effects in the short-term. These include pain killers and headache pills, as well as anti-sickness and anti-diarrhoea drugs.

Longer-term side-effects

It’s also known that some side-effects only develop in the longer term. For example, lipodystrophy, changes in body shape and blood fats, has been seen in people taking anti-HIV drugs for a number of months or years. Increased levels of blood fats can, in turn, increase the long-term risk of heart disease.

A rare, but serious long-term side-effect is called lactic acidosis.

There’s a lot more information about lipodystrophy and some other long-term side-effects later in this section.

Side-effects and a weakened immune system

If you have a very weak immune system there’s some evidence to suggest that you might be more vulnerable to side-effects, including painful nerve damage to the feet (peripheral neuropathy) and fat loss from the face, when you start taking anti-HIV drugs if your immune system is already severely damaged by HIV.

There’s a lot more information about peripheral neuropathy and fat loss later in this section.