Are Scented Candles Bad for You? What the Evidence Says

Updated 27 October 2026

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Written by IVNA London

For most people, burning scented candles now and then in a ventilated room is unlikely to cause harm. But any flame releases particles and gases into indoor air. People with asthma or sensitivity should take more care. Good habits make a real difference, and we show you which ones matter most. If you are choosing one, our guide to the best luxury scented candles covers what to look for.

What does a candle release?

Soot and fine particles, especially when the flame flickers or smokes, or in the moments after you blow it out.
Volatile organic compounds (VOCs) from the fragrance and the wax. These are what you smell, and every scented product gives them off in some amount.
Combustion gases, as with any flame, including cooking on a gas hob.

Indoor air studies find that candles add to indoor pollution. So do cooking, cleaning products and wood burners. The effect depends on how many candles you burn, for how long, and how well the room is ventilated.

What did the studies actually find?

Most scary headlines come from a handful of studies. Here is what each one really tested, and its limits.

The air freshener test behind "86%". In 2007 a US charity tested 14 air fresheners from shops in one part of California. It found chemicals called phthalates in 12 of them. It tested one sample of each and no candles at all, so it is old, small and about sprays and plug ins.
A test of scented candles. A 2014 study burned nine scented candles in sealed test rooms and measured what came off them. It found levels below health concern in normal use. It was paid for by a fragrance industry group, which is fair to know.
Newer work on tiny particles. A US team at Purdue University tested the air in a real test house. Scented wax melts gave off as many tiny particles as scented candles and gas hobs. The team said we still need to learn what these particles do to health.
A call for more research. A short 2023 article in a science journal, called "Beyond Aromatherapy", argued that heavy scented candle use needs more study.

The UK charity Asthma + Lung UK takes a calm view that we share. It says scented candles give off small amounts of some gases. But if you only use them now and then, they are unlikely to pose much of a health risk.

Who should take more care?

People with asthma or other breathing conditions, who may feel smoke or strong scent sooner.
People who get headaches or migraines from fragrance, most of all in small rooms.
Homes with babies or very young children, whose lungs are still growing.

How do you burn candles more cleanly?

Trim the wick to about 5mm before every burn, because long wicks smoke.
Keep it out of draughts. A flickering flame makes more soot, so keep candles away from open windows, fans and doorways.
Burn for no more than 4 hours at a time, then let the candle cool.
Ventilate during and after burning, even if that only means a window open a little.
Don't burn several at once in a small room. One good candle is plenty for most spaces.
Put it out if it starts to smoke, trim the wick and relight.

Two more habits help. Lift out any bits of wick or match from the melted wax, since debris makes the flame flare. Put the candle out with a snuffer or by dipping the wick, which cuts the smoke you get from blowing it out. More fixes in why your candle tunnels, flickers or smokes.

Does the wax matter?

Brands often claim that plant waxes like soy burn "cleaner" than paraffin. The evidence is mixed, and wick care and ventilation matter at least as much. See soy vs paraffin vs coconut wax.

Synthetic or natural fragrance: what does the label tell you?

You will hear that "synthetic fragrance" is the problem and natural oils are the fix. The truth is gentler. Essential oils are made of the same kinds of scent chemicals, and some can cause skin allergies. Natural does not mean risk free.

What matters more is how well the scent is made and checked. Good fragrance houses follow the IFRA Standards. This is an industry safety code that bans some ingredients and caps how much of others each product can use. It is voluntary, but every IFRA member must follow it.

In the UK, a candle whose scent could cause a skin reaction must carry a CLP label. Look for red diamond warning symbols and a line such as "Contains linalool. May produce an allergic reaction." This shows the maker has done the checks. It does not mean the candle is unsafe to burn.

So choose a brand that tells you who makes it, with a clear CLP label and proper care advice. Our luxury scented candles are handmade in England by skilled candle makers in the Essex countryside.

What are the flame free alternatives?

If you love scent but want less smoke, one of our luxury reed diffusers gives constant fragrance with no flame. It still releases fragrance VOCs, so ventilation still matters. See are reed diffusers safe?

Houseplants are lovely, but a 2019 review found you would need 10 to 1,000 plants per square metre to match an open window. Fresh air is still the best fix.

Quick answers

Do scented candles cause cancer?

There is no strong evidence that occasional candle use in a ventilated room causes cancer. Heavy use in closed rooms adds to indoor pollution, so moderation and fresh air are sensible.

Which candles are non toxic?

No candle is truly "non toxic", as any flame produces combustion products. Burn with good habits and ventilation, and you keep what it gives off low.

Are candles bad for your lungs?

Heavy use in a closed room can irritate sensitive lungs. Ventilate and burn in moderation.

Are air fresheners toxic?

Sprays and plug ins release VOCs, and one small US test in 2007 found phthalates in most of those it checked. Used lightly with fresh air, they are unlikely to harm most people. Sprays are the easiest kind to breathe in.

Enjoying candles, and when to choose a reed diffuser

If you love candles, burn them in short sessions with the wick trimmed, as above. Our Mayfair Library scented candle is made for slow evenings. Its warm vanilla, tonka and cedarwood make a room feel cosy and snug. For all day scent with no flame at all, a reed diffuser in the same scent, like the Mayfair Library reed diffuser, does the everyday work so the candle is only for when you want it.

See the full range of our luxury scented candles. They are vegan, with no palm oil.