SAN DIEGO -- Parents fighting their teens' drug use have one more weapon in their arsenal.

HairConfirm Prescription, a new home-based hair follicle drug test kit, is now on the market. The kit is the first of its kind, able to test for 12 different types of illegal and prescription drugs and report the amount of each chemical detected, with a longer window of detection than the standard saliva- or urine-based at-home drug test.

Drug use is revealed through hair analysis because hair growth is fed by the bloodstream. Makers say this makes a test that uses hair 5 to 10 times more sensitive than a test that uses saliva or urine.

Hair drug tests measure the molecules embedded in the hair shaft, preventing external contamination that can cause a false positive result.

"I can tell you first hand how easy it is for families to dismiss the visible signs of drug abuse in a loved one," said a HairConfirm customer who purchased the kit for a family member. "But numbers don't lie, and the detailed information provided by this product will help bring people together to deal with it."

Two-thirds of parents said they would ask their teenage son or daughter to take a home drug test as a way to keep him or her away from drugs, according to a 2006 survey of 2,064 parents by RT Strategies.

"HairConfirm is designed to help parents take a proactive role in preventing their children's illegal and prescription drug use," said Zeynep Ilgaz, CEO of Confirm BioSciences, the test's manufacturer.

"Talking with your child about drugs and taking preventive measures like hair drug testing can be a significant factor in preventing substance abuse."

HairConfirm Prescription is available from a variety of online vendors listed on the product website. The kit costs $89.99.