Tenofovir (Viread, also in the combination pills Truvada and Atripla) is processed by the body through the kidneys, and there is some evidence that people with other risk-factors for kidney disease (for example high blood pressure or diabetes) might have an increased risk of developing kidney problems when taking this drug.

The now rarely used protease inhibitor indinavir (Crixivan) can cause kidney stones, and their treatment might involve outpatient treatment or a short stay in hospital.

Your routine HIV care should involve regular tests to check on the health of your kidneys.

If you develop kidney problems then it may be necessary to change your HIV treatment or to have special treatment for your kidneys.

Lipodystrophy is the term used for changes in body shape. It was originally thought that the cause was protease inhibitors, but it now seems that some drugs in the NRTI class may be the main cause. The use of the drugs most associated with lipodystrophy - AZT and d4T - is now avoided as much as possible.

Body-fat changes seen in people taking HIV drugs can involve fat loss, fat gain, or a mixture of both. This may result in: increased waist size (without rolls of fat); increased breast size; fat gain around the back of the neck and upper back; fat gain around the neck and jaw; facial wasting, especially of the cheeks; wasting of the buttocks; prominent veins in the arms and legs (because of fat loss). Some people have developed small lumps of fat called lipomas, often in the limbs or trunk.

The abdominal fat gain in lipodystrophy is made up of hard fat that accumulates around the internal organs, causing the belly to feel taut and pushed out. This is different to the squeezable fat gained if people put weight on through over-eating or lack of exercise.

As noted above, the use of the drugs most associated with lipodystrophy is now avoided as much as possible. People who took either AZT or d4T and who switched to tenofovir (Viread) have experienced very slow returns of fat in the limbs.

Fat loss from the face can be repaired in a number of ways. The most commonly used technique involves injections of a product called New Fill  into the affected areas. This treatment is often available from HIV clinics so ask your doctor or another member of your healthcare team if this treatment is available to you.

Surgery can be an option for removing fat accumulation around the neck, and lipomas can also be surgically removed if needed.

Other possible treatments involve human growth hormone or anabolic steroids. Again, you can talk to your doctor about these.

Regular cardiovascular exercise and weight training has been shown to have some positive effect on fat gain.

People who have experienced body-fat changes have sometimes found this stigmatising – a visible sign that they are taking HIV treatment. The bodily changes can also affect the way that people feel about themselves.  If you have developed lipodystrophy and have felt this way, acknowledging your feelings and talking to somebody about them can be very helpful. Your HIV clinic should be able to talk to you about accessing talking therapies or getting treatment for depression if you think it would be helpful for you.

Anti-HIV drugs can also disrupt your metabolism – the way your body processes the things it needs to work properly.

Specifically, anti-HIV drugs can cause abnormal levels of blood lipids – cholesterol and triglycerides and also blood sugar.

Cholesterol

There are two types of cholesterol: HDL cholesterol, often called 'good' cholesterol, and LDL, or 'bad' cholesterol.

Levels of HDL cholesterol are often reduced in people with HIV and other chronic illnesses. High levels of LDL cholesterol indicate that you are at greater risk of heart disease, and increases in LDL cholesterol are often seen in people taking anti-HIV drugs.

If you have high LDL cholesterol, the following factors increase your risk of heart disease even further:

• Smoking.
• High blood pressure.
• A family history of heart disease.
• Being physically unfit.
• Being aged over 45 for men and over 55 for women.
• Insulin resistance or diabetes.
• High blood sugars.
• Being very overweight, particularly with a lot of fat around the middle.
• Use of stimulant recreational drugs like cocaine or amphetamines.

It is particularly important to monitor LDL cholesterol levels if you are taking a protease inhibitor.

Triglycerides

Triglycerides are fatty acids derived from fat, sugar and starches in food. These travel through the bloodstream and are stored in tissues or in the liver. Levels of triglycerides can be increased by some anti-HIV drugs.

Glucose

Glucose is a form of sugar found in the blood. High levels of glucose can increase the risk of heart disease. Levels of glucose can be increased by some anti-HIV drugs.

Insulin

Insulin is the substance produced by the body to control glucose levels in the blood. Some people taking anti-HIV drugs need to produce more insulin to keep their blood levels of glucose normal. This is called insulin resistance. It may be necessary to have your insulin levels tested.

Symptoms of metabolic change

Abnormal levels of fats and sugars in the blood can sometimes cause symptoms including:

• Tiredness.
• Dizziness (due to high blood pressure).
• Loss of concentration.
• More frequent urination.
• Thirst.

However, some people don’t notice any symptoms, even when they’ve had abnormal levels of fats and sugars for a long time and are at greater risk of heart disease.

Heart disease and anti-HIV drugs

Levels of fats in your blood may start to rise when you start HIV treatment, particularly if you are taking certain protease inhibitors. Sometimes they can increase so much that it’s necessary to change your diet, start exercising, or take a medication to control them.

Large studies of people taking protease inhibitors have shown that they have a slight, but nevertheless significant, increase in their risk of heart disease. Some (but not all) studies have also suggested that abacavir (Ziagen, also in the combination pills Kivexa and Trizivir) might increase the risk of heart disease, particularly for people who already have risk factors for heart problems.

If you have any existing risk factors for heart disease, your HIV treatment should be carefully chosen to ensure that it doesn’t raise the risk even further. And a 'risk' of heart disease does not automatically mean that heart problems will develop. A lot can be done to prevent this happening.

First of all, your cholesterol, triglyceride and glucose levels should be monitored at each routine clinic visit. This will mean that your doctor can spot any warning signs early.

Looking after your heart

There is also a lot you can do to help keep your blood lipids within safe limits. This includes eating a good diet with lots of fresh fruit and vegetables and without too much fat, regular exercise, and not smoking.

Lipid-lowering drugs

In some circumstances your doctor might prescribe what are called lipid-lowering drugs. These are used to treat heart disease and hardening of the arteries and include statins (to lower cholesterol) and fibrates (to lower triglycerides and also cholesterol). Some statins can interact with protease inhibitors, and both statins and triglycerides can cause their own side-effects, so your doctor will monitor you to see if these are developing.

Some drugs are also being investigated to see how effective they are at controlling glucose and insulin in HIV-positive people.

Most HIV drugs are processed by the body using the liver, and a small number of people have experienced liver problems when taking HIV treatment. In many cases, these people had other risk factors, for example infection with hepatitis B or C virus, treatment with other medicines that can harm the liver, or lifestyle issues, such as drug or alcohol use, that were damaging to the liver.

Your routine HIV care will involve blood tests to monitor the health of your liver. If you do develop liver problems, possible options include changing your HIV treatment or having additional treatment for your liver problems.

Changes in your diet may also help, so try and eat lots of fresh fruit and vegetables and avoid fatty food. Drinking too much alcohol and the use of some recreational drugs can also damage the liver or make existing liver problems worse. Your HIV clinic will be able to offer advice and support if you are worried about your alcohol or drug use.

Nerve damage can be a very painful side-effect of some anti-HIV drugs, and can also be directly caused by HIV itself.

Neuropathy is damage to the nerves, and the nerves that can be damaged by some anti-HIV drugs are in the limbs (and very rarely, male genitals). Therefore this side-effect is called peripheral neuropathy.

Peripheral neuropathy usually involves damage to the nerves in the lower legs and feet or, less commonly, the hands. The symptoms can range from mild tingling and numbness through to excruciating pain that makes it impossible even to wear a pair of socks. Usually both sides of the body are equally affected.

Other symptoms of neuropathy can include dizziness, diarrhoea and sexual dysfunction in men (inability to obtain or sustain an erection).

The two main drugs that can cause peripheral neuropathy are d4T and ddI. These drugs are now only used if there are no other treatment options available. There is some evidence that 3TC may involve a risk of peripheral neuropathy.

It can also be caused by other drugs prescribed for people with HIV, such as some antibiotics, TB drugs and therapies for Kaposi’s sarcoma (often abbreviated to KS).

If you do develop drug-related neuropathy, it is important that your HIV treatment is changed immediately (but do get your doctor's advice before making any changes to your medical treatment). Once the drug has been stopped, the neuropathy may continue to get worse for a couple of weeks, but then it nearly always goes away over time.

In the meantime, your doctor can prescribe treatments to reduce the pain. Trials have shown that a drug called L-Acetyl-Carnitine can help reduce the symptoms of neuropathy.

There are several different causes of nerve damage among people with HIV - for example HIV itself, other infections, or diet problems. It is therefore very important to tell your doctor if you have tingling, numbness or pain in your feet so that the cause can be properly investigated.