Can scented candles release toxic fumes that damage your lungs?

What's actually in it

Scented candles are made from paraffin wax (a petroleum byproduct), synthetic fragrances, dyes, and metal-core wicks. When they burn, the heat breaks down these ingredients into a cocktail of volatile organic compounds (VOCs) including formaldehyde, toluene, benzene, and acrolein. The scent you smell is a mix of fragrance chemicals and combustion byproducts.

In a closed room, these compounds build up quickly. Burning a candle for an hour can raise indoor VOC levels well above what you'd breathe outdoors on a busy street.

What the research says

A 2025 study in Front Public Health tested the volatile organic compounds released by scented candles and then exposed rats to the fumes. The researchers found oxidative stress, inflammation, and visible lung injury in the exposed animals.

Computer modeling of the individual chemicals showed that many of them have poor safety profiles for inhalation. Several can be absorbed through the lungs and distributed throughout the body. The combination of compounds was worse than any single chemical alone.

The damage wasn't limited to the lungs. The researchers found signs of systemic inflammation, meaning the fumes affect your whole body, not just your airways. Switching to beeswax or soy candles with cotton wicks and natural essential oils cuts down on the worst offenders. Or skip the flame entirely and use a cold-air diffuser.