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A drug is usually approved to treat a specific illness. Anything else it does is called a side effect.

Sometimes side effects can be helpful, but more often they are a problem. Side effects can be annoying, difficult and in rare cases, extremely serious.

In this booklet we mainly focus on side effects of HIV antiretroviral drugs (ARVs).

Side effects are also called adverse events or referred to as drug toxicity.

Do all drugs have side effects?

Every drug is likely to have some side effects for some people. In most cases these will be mild and easy to manage.

Sometimes they are so mild that they are not noticed. They usually only affect a small proportion of people.

Serious side effects, although possible, only occur rarely.

How common are side effects with HIV drugs?

Most HIV drugs have a low risk of serious side effects.

However, the information about potential side effects can sound worrying. Even common, over-the-counter, medicines like aspirin or paracetamol have many potential side effects (see Table 1).

Most people starting HIV treatment report one or more side effects.  Sometimes this is because when we start a treatment we are more sensitive to anything that happens, even though it may not be a side effect.

People in studies taking a placebo often report high rates of side effects.

Not everyone taking drugs will have the same effects. What is important is how they affect you and what you can do about them.

Table 1: Side effects listed for aspirin

Dyspepsia (digestive problems), nausea, vomiting. Less commonly, irritation of the gastrointestinal mucosa may lead to erosion, ulceration, gastrointestinal bleeding. Hepatotoxicity (liver toxicity), which occurs rarely.
Hypersensitivity reactions including urticaria (rash), rhinitis (nasal problems), angioedema and severe bronchospasm (blocked airways).
May cause salt and water retention as well as a deterioration in kidney function.

Symptoms vs side effects

The word symptom is usually used for any change in how you feel that you could report to your doctor. For example, feeling tired, or having diarrhoea are both symptoms that could be side effects.

Other side effects can only be seen after a lab test, for example, high cholesterol or raised liver enzymes.

The symptoms of many common side effects are similar to symptoms of illnesses.

Your doctor needs to know about every symptom in order to be able to decide whether it is caused by treatment (a side effect) or a different illness.

Different treatments are needed when a symptom relates to an illness.

1 July 2012