Experts have warned people against allowing "a bit of dirt" into their homes in the belief it will protect against asthma and other conditions.
The number of people with allergies has increased in recent decades
Some scientists have suggested that being exposed to infections early in life may have a protective effect.
The so-called "hygiene hypothesis" suggests cleaner homes may be behind rising rates of asthma and allergies.
But researchers at the London School of Hygiene and Tropical Medicine say the theory has yet to be proved.
In a report for the International Scientific Forum on Home Hygiene, they warned people against allowing dirt back into their home.
"Any suggestions that we should relax hygiene and sanitation in the developed world is irresponsible," they said.
The researchers suggested it would be impossible for people to allow dirt into their homes without also increasing their risk of contracting infections.
"Any attempt to provide 'controlled dirtiness' in the environment would inevitably raise the risk of invasive infection.
"'Controlled dirtiness' is not a feasible concept, raising questions such as: how often should people wash their hands or clean chopping boards; or how long washing should be delayed after exposure to dirty environments?"
However, they said people should take a balanced approach when it comes to keeping their home clean.
"We can be clean, hygienic and healthy without attempting to create a sterile environment in our homes or a sterile 'cocoon' around our infants."
They said further research is needed to identify the real threats to health in the home and to give families clear advice on what steps they need to take.
The researchers said there was no clear evidence to suggest that improvements in hygiene were behind rising rates of asthma, eczema, hay fever and other allergies.
"The relationship of the hypothesis to hygiene practice has not been proved," they said.
In their report, they suggested that there may in fact be other causes. They said changes to diet and exercise may be behind the increase.
Allergy UK urged people to take a more relaxed approach to keeping their homes clean.
"We've gone a little bit fanatical about making sure we kill off every possible bug that can come near us," said a spokeswoman.
"It doesn't hurt coming into contact with bacteria. We're not saying people should have dirty homes and kitchens but we should hold back on throwing so many chemicals at bacteria."