Horizon's Thalidomide: a necessary evil will be broadcast on Thursday on BBC2 at 2125 GMT.

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Thalidomide is once again being used in the UK to treat a variety of conditions, according to the BBC's Horizon programme.

The programme follows the progress of Sarah Craven who is treated with thalidomide at a Nottingham medical centre.

She has a rare disease which causes excruciatingly painful mouth and genital ulcers.

Sarah Craven suffers from painful ulcers

Sometimes the ulcers can be so painful that sufferers cannot talk or sit.

Sarah says that, after taking thalidomide, her symptoms cleared up within three weeks.

"It really is a miracle drug," she said.

Some 8,000 people around the world are living with the birth defects caused after their mothers took thalidomide in the early stages of pregnancy.

Pregnant

Horizon's Thalidomide: a necessary evil follows Sarah's dilemma as her illness returns while she is seven months pregnant.

After consultation with her doctor and a weekend of terrible pain, she decides to take the drug, which is not licensed in the UK.

A specialist tells her it is unlikely the baby will be affected as it is fully formed and thalidomide is only a major risk for women in the early stages of pregnancy.

However, he admits this is unknown territory.

Fortunately, Sarah's baby Jake is born with all his limbs intact.

US licence

Thalidomide was licensed for use in the USA in July.

The move follows pressure by Aids patients who have been importing the drug and using it on the black market after it was found to alleviate the symptoms of diseases of the immune system.

Thalidomide was discovered by accident in 1954 by chemists in Germany who were trying to produce an anti-histamine.

The drug they manufactured did not work as an anti-histamine, but it was found to be an effective tranquilliser with no harmful side effects.

In the 1950s and 60s, thousands of children were born without limbs

Demand for the drug rose and it was used to treat many anxiety conditions, including morning sickness.

Agnes Donellan was one of the mothers who took the drug. Her son Kevin was born without fully formed arms or legs.

He was one of many and doctors feared an epidemic.

However, they did not know the cause of the disease. Some thought it was due to a virus or atomic leaks.

Thousands affected

It took five years before an Australian obstetrician, William McBride, traced it to thalidomide, marketed as Distaval.

German scientists experimented on monkey foetuses given thalidomide

His research was published in 1961, but the drug was not banned until 1962. Some 12,000 children in 46 countries had been affected by then, with only 8,000 of them surviving past the first year of life.

German researchers experimenting on monkey foetuses confirmed his research, but they did not know why the drug caused these results.

This is still a mystery today.

False limbs

Doctors have tried to make amends to thalidomide victims by putting them through operations and fitting them with false limbs.

Keven Donellan says his limbs were "useless" and made him feel like a robot. The legs were very heavy and caused balance problems.

Thalidomide cleared up skin lesions caused by leprosy

Despite the 1962 ban on thalidomide, by 1965 it was back in use in Israel.

A doctor treating leprosy patients used old supplies to give pain relief to people with skin lesions.

The lesions cleared up overnight. It was found that the drug could regulate the immune system.

Cancer treatment

In 1992, a Boston researcher hit on thalidomide as a possible treatment for cancer.

He was searching a database for drugs which stop blood vessels from growing.

Many cancer depend on the growth of blood vessels to transport the disease.

After his discovery, US scientists began clinical trials to test the drug's effect on different cancers, including advanced brain tumours.

It has been found that thalidomide shuts down the blood supply to tumours.

It has been used on 80 patients over the last 15 months.

Scientists say 60% show stabilisation of their cancer or regression. In some cases, the tumour has disappeared altogether.

Moral dilemma

The trials and the illegal use of the drug to treat the worst effects of Aids brought pressure on the US authorities to license the drug.

Scientists are divided over whether thalidomide should be used

"It is a moral dilemma," said a spokesman for the Food and Drug Administration.

"The drug can bring incredible hope to certain people, but can destroy the lives of other members of society if used incorrectly."

In Brazil, a new generation of thalidomide victims are growing up after mothers used the drug in the early stages of pregnancy to ward off leprosy.

They did not understand the risks involved.

Kevin Donellan said: "It makes me very angry. It has been allowed to happen yet again when it is so unnecessary."

Risks

US officials are trying to reduce the possibility of the drug being misused by pregnant mothers by saying those who use it must be taking contraceptives.

But Dr Claus Newman, a specialist in birth defects based at Queen Mary's hospital in Roehampton says: "Even with all the precautions we can set up there will continue to be risks of more congenitally malformed babies being born."

Doctors are divided on whether thalidomide should be consigned to history or used to treat specific conditions.

Some describe it as "a necessary evil".

Genetic condition

Most doctors appear agreed on one thing: that thalidomide birth defects cannot be passed from one generation to another.

However, there have been cases where people born without limbs have gone on to have limbless children.

Originally, these people's condition was thought to have been caused by their mothers taking thalidomide.

However, doctors now think they may have a genetically inherited condition.