There is no doubt that injecting into the groin is dangerous. It distresses me to see how quickly some people move into using their groins. Some still have good veins left in their arms. Others have failed to look after their arm veins properly, for example by using clean equipment, alternating sites, injecting carefully and taking breaks from injecting. Those who have started using their groins often don't think of returning to their arm veins when these have recovered. The vein that runs through the groin is called the femoral vein. It is an important part of the blood system, and should be treated with respect. It runs close to the femoral artery and the femoral nerve, which are also very important structures. The vein is nearest of the three to the midline. If you put your finger over the pulse in your groin, and then move inwards about two fingers' breadths, you should be over the femoral vein. There are three common but serious dangers from injecting here, and lots of other less common ones which I have not got the space to describe.

1. Each time you inject into the vein it causes a little damage, and this gets worse over time. The big danger is that clots can form in the vein, causing deep vein thrombosis. This can lead to long-term damage to the blood drainage system in the legs, causing swollen ankles, poor circulation and ulcers and abscesses. Part of the clot can break off, and then be carried to the lungs, where it blocks off a major blood vessel. This is called pulmonary embolism, and can lead to sudden death.

2. Blood can leak from the injection into the deep parts of the groin. It can then get infected, and cause an abscess, which is a collection of pus. This is a bad place to have an abscess. The pus may not come out at the surface, but may force its way through into the muscles of the leg, into the bladder or into the back passage. This type of false connection caused by infection is called a fistula. It can be very difficult to treat, and usually requires a number of operations, and a great deal of misery.

3. Injection may occur by error into the artery or the nerve. Damaging the nerve may cause long-lasting pain and lack of feeling in the upper leg. Injecting into the artery can cause spasm of the artery, and an interruption of blood flow into the leg. There are several injectors who have lost a leg in this way. This is particularly likely if crushed tablets are injected, but can occur with methadone or heroin.

Does all the happen to everyone? Probably not. There are some people who inject in the groin over quite long periods without problems. But if your fiance continues to inject twice a day over the next ten years, he will inject himself at least 7000 times. It becomes very likely he will run into trouble. He will be very lucky to be still in good health when your son is old enough to leave school. If a user starts injecting in his groin, he should get back to using his arm veins as soon as possible. Or try injecting into his muscle if it is a pharmaceutical drug (the drug clinic will tell him how)*. Or give up injecting