Scientists behind Fast, or Fortified Amino Scalp Therapy, say their product can grow hair by as much as two inches in just one month, which is double the usual rate.

Tests of the product suggest that the rate of growth increases the longer a person uses the products, the Daily Mail reported.

There is already a long waiting list of 5000 people for the shampoo and conditioner, which goes on sale in the UK on January 23.

The shampoo, which is made from natural herbs and organic amino acids, works by stimulating growth in the follicle.

However, while it helps those whose hair has fallen out through cancer, the shampoo is not a remedy for baldness because it cannot stimulate new hair growth, rather only promote the growth of existing hair.

Clinical trials have been carried out over the past 12 months on 1,000 men and women, who were asked to wash their hair with the shampoo and conditioner daily.

They had their hair dyed, photographed and measured for growth every six weeks.

After the first six weeks, the hair of half the subjects tested showed increased growth – on average 17 percent more than normal.

However, after another six weeks’ use of Fast all the men and women’s hair had increased growth.

On an average hair grew 30 percent faster than usual after 12 weeks, although one subject experienced a 99 percent boost in hair length.

The shampoo and conditioner will cost 24.99 pounds together when they go on sale this month.