How Bad are Scented Candles—Really? Health Risks and Safe Alternatives We Love

What Are Candles Made Of (and What They Release When Burned)

Most conventional candles are made from paraffin wax, a petroleum byproduct. The wicks are typically cotton or paper, though some still contain metal cores. Then there's the fragrance, which is often a blend of chemicals designed to fill a room with scent.

When you light that wick, a chemical reaction begins. The flame vaporizes the wax, which then combusts to produce light and heat. Sounds simple enough. But the process also releases a complex mixture of compounds into your home's air. Research shows that burning scented candles emits volatile organic compounds (VOCs) like toluene and formaldehyde, along with fine particulate matter (the tiny particles that make up soot). 

According to the EPA, indoor concentrations of many VOCs are consistently two to five times higher than outdoor levels, and activities like burning candles can push those numbers even higher.

Are Scented Candles Bad for Your Health?

You might not connect that headache or scratchy throat to the scented candle burning on your coffee table, but it could be the underlying cause. VOC exposure is linked with eye, nose, and throat irritation, headaches, dizziness, and nausea. 

Here’s why. The particulate matter released by scented candles is small enough to penetrate deep into your lungs, and chronic exposure has been associated with respiratory issues, worsened asthma symptoms, and cardiovascular strain over time. For those with sensitive skin or existing allergies, prolonged VOC presence indoors may even trigger skin irritation or itchiness.

Studies have found that under normal use conditions—like burning a candle in a reasonably ventilated room for an hour or two—exposure levels for most people fall below established health thresholds. But if you're burning scented candles daily or in small, poorly ventilated spaces, exposure to VOCs and other particulate matter can impact your health.

Who's Most at Risk When Burning Candles (Including Babies and Pets)

Certain groups are more vulnerable to candle emissions. Babies and young children, for instance, have developing respiratory systems that are more susceptible to irritation. And those with asthma, allergies, or other respiratory conditions are more likely to notice symptoms flare up around scented candles. Pregnant women may also want to limit exposure, as some VOCs have been linked to developmental concerns.

Have furry family members? You'll want to pay attention to the type of scented candles you buy, too. The ASPCA notes that essential oils—commonly used in "natural" candles—can be problematic for pets. Cats are especially sensitive because they lack certain liver enzymes needed to metabolize these compounds. 

Dogs aren't immune, either. Oils like tea tree, eucalyptus, peppermint, and citrus are known irritants for both cats and dogs. If you're burning candles or using diffusers around pets, stick to safe essential oil scents, like cedarwood, lavender, and rosemary, use them in well-ventilated areas, and watch for signs of distress like drooling, coughing, or lethargy.