For allergy sufferers, determining what it is in their environment that causes their unpleasant reactions can be almost as unappealing as the allergy symptoms they suffer.
The skin on their back is pricked -- perhaps 20 to 60 times -- with different allergens, with the body's reactions hopefully revealing the culprits.
For these people, a home allergy test promises an answer without the unpleasant diagnostic test or its expense. Using a $50 test, by pricking their finger and sending their blood to a lab, customers can have themselves tested for 10 of the most common allergens -- which make up 90 percent of allergies, according to the test makers.
But some doctors and advocates say the test is unreliable, and creates risks that may be harmful or even fatal.
"I don't think there is much value personally, because you're just doing tests without taking a history," said Dr. Anne Miranowski, an allergist with The Pediatric Lung Center in Fairfax, Va. "We determine what tests are necessary based on a person's history. We don't indiscriminately test before we see the patient."
The problem, she said, is that allergy tests can often show an antibody reaction to foods the patient has not had any problems with. Without a doctor to interpret results, patients may opt to remove foods from their diet for no reason.
"They may decide 'I'm allergic to milk.' Now they're eliminating a healthy source of calcium and protein from their diet ... when in fact they were never allergic to begin with," Miranowski said.
And many of the tests may be simply unnecessary.
"Would you go for cancer screening right now, you and I? What does it mean if you haven't had symptoms of cancer?" said Dr. Leonard Bielory, an allergist with the University of Medicine and Dentistry of New Jersey, and a fellow of the American Academy of Allergy, Asthma and Immunology.
At the same time, tests can show a negative result, leading the person to do something more dangerous.
"Because tests are normal does not mean things are good," Bielory said.
A case in which a food comes up negative but causes anaphylaxis -- a severe, whole-body allergic reaction -- can prove fatal.
That concern is the reason why Gina Clowes, founder of the blog allergymoms.com, said she would advise against these tests and wouldn't use them with her son, Daniel, who has a number of food allergies.
"Allergic symptoms can run the gamut from annoying to life threatening," she said. "If you're having serious symptoms, for me or my children, only a real M.D. would do when diagnosing or treating them."
California-based ImmuneTech manufactures MyAllergyTest, which tests for reactions to 10 common allergens. It has been approved for use by the Food and Drug Administration.
"One of the greatest benefits is it makes allergy testing accessible to everyone," said Kathryn Fairchild, president of ImmuneTech. "It's a great opportunity for people to take health care into their own hands."
While doctors' concerns seem to be based on a patient using the test to self-diagnose their allergies, Fairchild said the test should not be used without consulting a physician, and should be able to help patients who could not otherwise afford an allergy test.
"Physicians [are] reticent to send patients to an allergist because the patients may not get to an allergist," Fairchild said.