Are scented candles toxic to breathe indoors?

What's actually in it

Scented candles get their smell from fragrance oils blended into paraffin or soy wax. When you burn them, the wax and fragrance don't just evaporate cleanly. They release a mix of volatile organic compounds (VOCs) including formaldehyde, toluene, benzene, and acrolein. Some candles also produce fine particulate matter and soot.

Paraffin candles, which are made from petroleum, tend to release more VOCs than soy or beeswax candles. But all scented candles produce some level of chemical emissions because the fragrance itself breaks down when heated.

What the research says

A 2025 study in Front Public Health identified the specific VOCs released by scented candles and then tested their effects on living tissue. The researchers first profiled the chemicals using computer modeling to predict how they'd behave in the body. Then they exposed rats to scented candle emissions and examined the results.

The rats showed clear signs of oxidative stress, meaning the chemicals overwhelmed their cells' natural defenses. Their lung tissue showed inflammation and visible injury under the microscope. These effects happened at exposure levels comparable to burning candles in a normal-sized room.

The computer modeling part of the study flagged several of the VOCs as easily absorbed by the lungs and potentially toxic at low doses. Some had properties that suggest they could build up in the body with repeated exposure.

If you like candles, beeswax or soy candles with no added fragrance produce far fewer VOCs. Opening a window while burning any candle also helps clear the air.