If you’ve ever Googled “are candles toxic” at 11pm while a candle flickers on your nightstand, you’re not alone. It’s one of the most searched questions in the candle world — and honestly, it deserves a real answer.
Not a panicked one. Not a dismissive one. Just an honest look at what the science says, what it doesn’t, and what it means for the way you choose to burn.
Let’s get into it.
The short answer
Many conventional candles are made from paraffin wax, a byproduct of petroleum refining. When burned, paraffin candles can release volatile organic compounds, or VOCs, including compounds such as benzene and toluene. Benzene is a known carcinogen, while toluene can irritate the respiratory and nervous systems at higher exposures.
Candles can also produce soot and particulate matter, which may irritate the respiratory system — especially in small, poorly ventilated rooms. Some mass-market scented candles also use vague fragrance blends that may contain phthalates, a group of chemicals linked to endocrine disruption.
So: are candles bad for you?
The honest answer is: it depends on what they’re made of, and how you burn them.
What’s actually inside many conventional candles
Walk into any big-box store and pick up a candle. Chances are, it contains some combination of the following:
Paraffin wax.
Paraffin is a petroleum byproduct — inexpensive, widely used, and not something we believe belongs in a candle you burn regularly at home. When burned, it can release soot, particulate matter, and volatile organic compounds into the air, especially in small or poorly ventilated spaces. The exact exposure varies from candle to candle, but the choice is straightforward: if you care about what you breathe in your home, start with the wax. Plant-based waxes like coconut and soy are a cleaner, more thoughtful alternative.
Vague fragrance blends.
The word “fragrance” on a label can legally refer to a blend of many ingredients, and not all brands disclose what’s inside.
The concern isn’t synthetic fragrance itself. Thoughtfully chosen aroma ingredients — including synthetic ones — can make a scent safer, more stable, and more nuanced than naturals alone. The issue is fragrance without transparency, especially blends that may contain phthalates or unnecessary additives.
Questionable wicks.
Lead-core wicks are banned in the U.S., but wick materials still matter. Choose candles from brands that clearly disclose what their wicks are made from, and look for cotton, wood, or paper-core wicks with no lead or metal core.
The ventilation factor
Lighting a candle changes more than the mood of a room. It changes the air, too.
That matters because candles are often burned in the most personal spaces in our homes — bedrooms, bathrooms, living rooms, home offices — the places where we breathe, rest, work, and unwind.
That’s why how you burn matters almost as much as what you burn.
Any flame will affect indoor air to some degree. But a cleaner, well-formulated candle burned in a ventilated room is very different from several heavily fragranced paraffin candles burning for hours in a small, closed space.
Room size, airflow, burn time, wax type, wick, and fragrance load all shape what ends up in the air. Better ingredients reduce what’s released in the first place. Ventilation helps prevent buildup.
The simplest rule: choose cleaner candles, crack a window when you can, and avoid long burns in small, sealed rooms.
What “clean” actually means
The term gets thrown around a lot, so here’s what it should actually mean:
Wax: Coconut wax, soy wax, or beeswax instead of paraffin. These are plant-derived or natural alternatives that avoid petroleum-derived wax and tend to produce less soot when properly formulated and burned.
Fragrance: Carefully selected aroma ingredients — natural and synthetic where appropriate — that are phthalate-free, IFRA-compliant, and free from unnecessary harsh additives.
Wick: Cotton, wood, or paper-core wicks with no lead or metal core.
Vessel: Ideally something you can reuse, because the vessel is often the most resource-intensive part of the whole candle.
At Siblings, this is the standard we’ve held ourselves to since we launched. Our candles use an all-natural coconut and soy wax, clean fragrance and essential oils, and lead-free wicks — no paraffin, no phthalates, no parabens, and no sulfates. We also think a lot about what happens after the burn, which is why our wax comes in a refillable system rather than a single-use jar.
Signs your candle might not be as clean as the label suggests
It smokes heavily or leaves black soot on the jar
The scent is overpowering before it’s even lit
The label says “fragrance” without any further information
The brand doesn’t disclose its wax, wick, or fragrance standards
There’s no mention of what the wick is made from
Simple ways to burn more cleanly
Even with a great candle, a few habits make a real difference.
Trim your wick before every burn.
A wick longer than about 1/4 inch produces more soot and burns less evenly. Keep it short.
Burn in a ventilated space.
Especially in smaller rooms, open a window slightly or keep the door open. Fresh air circulation makes a meaningful difference.
Don’t burn for more than 3–4 hours at a time.
Longer burns can produce more soot, overheat the vessel, and affect how evenly the wax burns. Let it cool, then relight.
Extinguish cleanly.
Blowing out a candle releases a puff of smoke and can contaminate the wax with soot. Use a snuffer when possible.
Mind the space.
A bedroom, bathroom, or home office is usually smaller and less ventilated than a living room. Be more selective about what you burn in those spaces.
The bottom line
Candles aren’t inherently bad for you. But many candles sold at scale are made with ingredients that are worth thinking twice about, especially if you burn them often or in small, enclosed spaces.
The good news is that cleaner options exist. You don’t have to give up the ritual — the soft light, the scent, the way a candle shifts the feeling of a room. You just have to be a little more intentional about what’s in it.
That’s a swap worth making.
Siblings candles are made with all-natural coconut and soy wax, clean fragrance and essential oils, lead-free wicks, and compostable packaging. Every candle is designed to be refilled — because the cleanest candle is one that doesn’t end up in a landfill.
