Concern at self-test health kits
Self-test health kits could do more harm than good, consumer group Which? has warned.
Which? asked medical experts to examine six kits testing for early signs of diseases like prostate cancer.
It claims the tests, sold online or at chemists, could be a useful tool but may cause unnecessary worry or give false reassurance.
Boots, which makes two of the kits, said they should always be used with advice from a GP or pharmacist.
Which? questioned 64 members of the public about six widely available home testing kits.
The kits were also examined by Dr Danielle Freedman from the Royal College of Pathologists and GP Dr Paul Singer.
The independent consumer group said problems found with the kits included a lack of clear information, difficulty using them, confusing language, the possibility of false alarms or false reassurance, and misleading naming.
Which? chief executive Peter Vicary-Smith said: "Self-test health kits could be a useful tool, but the lack of clear information about how to use them could do more harm than good.
"As your GP may well have to carry out their own tests to confirm a positive diagnosis anyway, you may be better off saving your money and going straight to your GP."
Which? said it was passing its findings to the body that regulates medicines and testing devices, the Medicines and Healthcare products Regulatory Agency (MHRA).
It said it was concerned that some men who get a negative result with the prostate check may conclude they are in the clear even though the test carries a warning that they could still have cancer.
Dr Sarah Cant of The Prostate Cancer Charity said it did not encourage the use of prostate self-test kits.
They cannot diagnose a specific prostate disease, she said, or give men the chance to talk through concerns with a health professional.
She added: "We are concerned that the use of self-test kits may risk men's health - either by giving them false reassurance that they are healthy or by causing unnecessary anxiety by suggesting they have something wrong with their prostate.
"Any man who wants to take a test to see if he may have a problem with his prostate should first of all speak to his doctor."
The charity Diabetes UK said it would not recommend people use a self-testing kit if they are worried they have the condition.
Clinical advisor Libby Dowling said: "Self-testing results might not be accurate as blood glucose levels vary in all individuals during any given day and people might be falsely reassured.
"In addition, a positive diagnosis can only increase anxiety if someone does not have access to information and advice provided by a trained healthcare professional at hand."
Jessica Harris of Cancer Research UK said: "Using testing kits like these can do more harm than good for some people."
She added: "If you have any concerns about bowel or prostate cancer, either because you are worried about your risk of the disease or about an unusual change in your body, it's a good idea to go and see your doctor."
A spokesperson from Boots - which makes two of the kits - for bowel problems and blood glucose - said: "Boots UK recommends that home testing kits should not be used in isolation and should always be used with advice from a GP or pharmacist.
"All Boots pharmacists are fully trained and qualified to deal with all aspects of home testing kit use. It is advisable for customers to consult the pharmacy team prior to taking the test and ensure that they read and strictly follow the written instructions in the kits.
"All home testing kits available in Boots stores comply with European Medical Devices regulations, which ensure that they are safe, measure results accurately, and all contain comprehensive information leaflets. These products are designed as a basic screen to direct people with concerns to their GP."
Patrick Kirby of Valimedix Ltd, which makes the prostate test, said: "The PSA test is a widely used method of assessing PSA levels and can be a valuable tool providing an indication of the possible prostate abnormalities."
A Department of Health spokesperson said: "We urge people to be cautious when using home-testing kits.
"Anyone who is concerned that they may be suffering from an infection or illness should contact their GP practice, pharmacist or other health professional for advice.
"NHS Direct can also provide advice on 0845 46 47."