They can add a hint of romance to a meal or make taking a bath a real luxury.
But scented candles can be bad for your health, say scientists.
The smoke produced by many of them is laced with toxins linked to cancer, asthma and eczema.
The odd candle is unlikely to do any harm, but we should avoid using them day after day in bathrooms and other poorly ventilated rooms, say the researchers.
Warning: Using scented candles in poorly ventilated rooms such as bathrooms can increase exposure to cancer-causing toxins
The U.S. researchers burnt a range of candles in the laboratory and collected and tested the substances given off. This showed that those made of paraffin wax, the most common type, released potentially harmful amounts of chemicals such as toluene and benzene.
Some of the pollutants have been linked to cancer, while others could trigger asthma attacks or skin complaints, the American Chemical Society's annual conference heard.
Most of those on sale in Britain, including many scented ones, are made of paraffin wax, a byproduct of the petroleum industry.
Beeswax and soy candles, which are more expensive, were given a clean bill of health in the tests.
Researcher Dr Amid Hamidi, of South Carolina State University: 'An occasional paraffin candle and its emissions will not likely affect you.
'But lighting many paraffin candles every day for years or lighting them frequently in an unventilated bathroom around a tub, for example, may cause problems.'
Dr Noemi Eiser, of the British Lung Foundation, echoed the advice. She said: 'We would like to reassure people that occasional use of paraffin candles should not pose any risk to their lung health.
'However we would advise people to take sensible precautions when burning candles, such as opening a window to keep the room ventilated to minimise the amount of emissions breathed in.'
But Dr Joanna Owens, of Cancer Research UK, said: 'There is no direct evidence that everyday use of candles can affect our risk of developing cancer.'
She said it more important to focus on the risk factors that there was hard evidence for, such as smoking, alcohol, obesity, unhealthy diets, inactivity and heavy sun exposure.
The British Candlemakers' Federation said an authoritative study two years ago concluded that candles, including those made of paraffin wax, did not pose a health risk.
Ref: dailymail.co.uk
