Are Scented Candles Bad for You? What the Research Actually Says

By Kristina Braly, MD — Founder, AEMBR

Are scented candles bad for you? It's a question I get almost every week — and one I asked myself long before I ever thought about making candles. As a physician, I'm trained to look at the actual evidence, not the headlines. And when I started reading the research on candle emissions, I found something more nuanced than the alarming articles circulating on social media: some candle ingredients are genuinely worth scrutinizing, others are dramatically overstated as risks, and the quality of what you burn matters enormously. Here's what I found — and what I changed in my own home as a result.

What Happens When a Candle Burns?

Combustion is chemistry. When a candle burns, the wax vaporizes, travels up the wick, and combusts with oxygen. What enters your air depends on three variables: the wax type, the fragrance formulation, and the quality of the burn (wick size, airflow, how the candle is cared for).

The byproducts of that combustion include:

• Particulate matter (PM2.5): fine particles that can penetrate the lungs
• Volatile organic compounds (VOCs): gases released during combustion
• Soot: carbon particles from incomplete combustion
• Fragrance-derived compounds: whatever is in the fragrance oil — including, in conventional candles, potentially phthalates and synthetic aroma chemicals

The key word is potentially. Not all candles emit the same compounds. And the concentration and duration of exposure matters as much as the presence of a compound at all.

Paraffin Wax: The Legitimate Concern

Paraffin is a petroleum byproduct — it's what most mass-market candles are made from. When paraffin burns, it can release small amounts of benzene and toluene, both recognized carcinogens by the International Agency for Research on Cancer (IARC).

The nuance: studies measuring these compounds have generally found them at low concentrations under normal room ventilation. A 2014 study published in Science of the Total Environment found that paraffin candles do release detectable VOCs, but typical indoor levels from occasional use remained below exposure thresholds associated with health effects in most of the populations studied.

That said — "below thresholds in occasional use" is different from "no concern." If you're burning candles daily in a small, poorly ventilated space, paraffin wax cumulative exposure deserves attention. As a physician, I wouldn't categorically alarm my patients over a single paraffin candle burned weekly in a ventilated room. But I also wouldn't choose paraffin when cleaner alternatives exist. That's why AEMBR uses a coconut-apricot wax blend — not paraffin, not soy alone.

The "Scented Candles Cause Cancer" Headline Problem

You've probably seen some version of this: "Scented candles are as harmful as cigarettes." Let me be direct — that claim is not supported by the research literature as applied to normal candle use.

The studies that generate these headlines are typically chamber studies: candles burned in controlled enclosures with limited ventilation, measuring peak VOC concentrations under conditions that don't resemble real-world use. They detect compounds. They do not establish disease outcomes at household exposure levels.

The IARC classification most often cited covers benzene as a group 1 carcinogen — meaning there's sufficient evidence of carcinogenicity in humans at established exposure levels. What those studies do not say is that burning one candle in your living room one evening a week produces benzene at a level approaching any established harm threshold. Dose and duration are everything in toxicology.

I find these headlines frustrating because they create fear without useful information. What actually helps: choosing cleaner wax, choosing cleaner fragrance, burning with good ventilation, and trimming your wick.

Soot: The Overlooked Variable

Black soot deposits around the container rim or on nearby walls are a visible sign of incomplete combustion — meaning the candle isn't burning efficiently, and is releasing more particulate matter into your air than it should.

Soot is primarily caused by:

• Oversized or untrimmed wicks — the single most common cause
• Drafts that disrupt the flame
• Poor wax quality that doesn't vaporize cleanly
• Synthetic additives in lower-quality fragrance oils

A clean-burning candle — well-wicked, properly formulated wax, quality fragrance — produces dramatically less soot. Wick trimming to ¼ inch before each burn is the single highest-impact candle care habit most people skip.

Phthalates in Candle Fragrance: The Real Issue

Here's where I have a stronger concern than VOCs from wax: the fragrance. Specifically, phthalates.

Phthalates are plasticizing compounds historically used in fragrance oils to extend scent longevity and improve throw. They're also classified as endocrine disruptors — compounds that can interfere with hormonal signaling. The most studied phthalates (DEHP, DBP, BBP) are associated in the research literature with reproductive toxicity, developmental concerns in children, and thyroid disruption at sustained exposure levels.

The problem: fragrance formulations are protected as trade secrets under U.S. law. A candle labeled "scented" or even "naturally scented" can contain phthalates without disclosing it. The word "fragrance" on a label is a legal black box.

This is precisely why I formulated AEMBR candles to be phthalate-free — and why I insist on full fragrance oil documentation from every supplier we use. As a physician, endocrine disruptors in a product you're warming and diffusing into your home air is not a theoretical concern. It's the concern I take most seriously.

Our full candle collection uses only phthalate-free fragrance oils, and every AEMBR candle burns in coconut-apricot wax — no paraffin.

Coconut and Apricot Wax: Why the Blend Matters

Coconut wax burns cleaner than paraffin — lower combustion temperature, less soot, more efficient fuel-to-scent conversion. Apricot wax improves scent throw and creates a smoother, more even burn pool. The blend combines both properties: a clean, slow burn with strong fragrance performance without requiring synthetic amplifiers or phthalate-based fragrance carriers.

Compared head-to-head:

Indoor Air Quality: Practical Context

The EPA estimates that indoor air can be 2–5 times more polluted than outdoor air, and sometimes more, due to the accumulation of VOCs from furniture, building materials, cleaning products, and yes — candles. But context matters. A candle's contribution to indoor VOC load is a fraction of what comes from conventional cleaning sprays, air fresheners, and off-gassing synthetic materials in the home.

If you want to meaningfully improve indoor air quality while keeping candles in your life, the highest-impact interventions are:

1. Ventilate: crack a window when burning, or burn for shorter periods
2. Choose cleaner wax (coconut, apricot — not paraffin)
3. Verify fragrance oil is phthalate-free
4. Trim your wick before every burn
5. Replace conventional cleaning sprays and air fresheners — their cumulative VOC contribution in most homes exceeds candle contribution significantly

For a deeper look at what goes into clean fragrance oils specifically, see my post What's Actually in Fragrance Oils? A Physician's Ingredient Guide. And for how VOCs from cleaning products compare to candle emissions, read What Are VOCs and Why Do They Matter in Cleaning Products?.

What About Essential Oil Candles vs. Fragrance Oil Candles?

Essential oils are marketed as the "natural" alternative to synthetic fragrance. The reality is more complicated. Essential oils are biologically active compounds — many are terpenes, which do oxidize at combustion temperatures and release their own VOC compounds. Limonene (from citrus oils) and linalool (from lavender) have been detected in indoor air from essential oil diffusion and can react with ozone to form secondary pollutants.

That's not a reason to avoid essential oils — it's a reason to apply the same scrutiny to "natural" fragrance that you'd apply to synthetic fragrance. The source matters less than the specific compounds and their concentrations. A properly formulated phthalate-free fragrance oil can be a safer option than an unvetted essential oil blend in some contexts.

The standard I set for AEMBR: every fragrance oil supplier provides documentation confirming phthalate-free formulation, IFRA compliance, and no carcinogen-listed compounds. That's what "physician-formulated" means in practice — not just a marketing phrase, but documented ingredient accountability.

The Honest Risk Summary

Here's what I'd tell a patient asking this question in my office:

• Paraffin + phthalate-filled fragrance candles burned daily in unventilated spaces: Worth replacing. The cumulative exposure profile is unfavorable, especially for children and people with respiratory sensitivities.
• Conventional scented candles burned occasionally in ventilated rooms: The research does not support alarm. But given cleaner alternatives exist, why not choose them?
• Clean-wax, phthalate-free fragrance candles burned as directed: The residual risks are minimal and consistent with normal background VOC exposure in any home. This is what I burn.

The question "are scented candles bad for you?" doesn't have a single answer — it depends on what's in the candle. The more useful question is: what's actually in the candle you're burning?

What to Look For When Choosing a Candle

AEMBR Candles: The Standard I Set for My Own Home

When I started AEMBR, I wasn't trying to build a candle company. I was trying to find a candle I was comfortable burning around my kids — and failing to find it. The clean candle market at the time was mostly soy candles with vague fragrance sourcing and no documentation behind the "natural" claims.

I spent months testing wax blends and fragrance houses before I had a formula I'd stand behind publicly. Every AEMBR candle:

• Burns in a coconut-apricot wax blend — no paraffin
• Uses phthalate-free, carcinogen-free fragrance oils with IFRA documentation
• Is hand-poured in Houston, Texas
• Has a documented burn time — our standard vessels burn approximately 75–80 hours, Valkyrie 3-wick candles up to 120 hours
• Contains no synthetic dyes

That's what the physician-formulated standard looks like in practice: documented, specific, and auditable — not a label claim.

Browse the full collection: AEMBR Candles

Frequently Asked Questions

Are soy candles safer than paraffin candles?
Generally yes — soy burns cleaner with less soot and avoids the benzene/toluene profile of paraffin. But the fragrance oil still matters: a soy candle with phthalate-containing fragrance is not meaningfully "safer" than a paraffin candle with clean fragrance in that dimension. Evaluate both wax and fragrance.

Can candles affect indoor air quality?
Yes, especially when burned frequently in poorly ventilated spaces. But their contribution to indoor VOC load is typically smaller than that of cleaning sprays, aerosol air fresheners, and off-gassing building materials. A clean-wax, phthalate-free candle burned with the window cracked is a low-risk choice.

Are "aromatherapy" candles safer?
Not automatically. "Aromatherapy" is unregulated as a label claim. It often just means the fragrance is essential-oil-based, which — as discussed above — has its own VOC profile. Ask for phthalate-free documentation and wax type disclosure regardless of how the candle is marketed.

How do I minimize candle emissions?
Trim your wick to ¼ inch before every burn. Burn in ventilated spaces. Choose coconut or apricot wax over paraffin. Verify phthalate-free fragrance. Don't burn for more than 3–4 hours at a time. Let the wax pool reach the edges before extinguishing to prevent tunneling.

Do scented candles cause cancer?
The research does not support this conclusion at normal household exposure levels. Some compounds released during candle combustion — particularly from paraffin wax — are classified carcinogens at sustained, high-concentration exposures. Normal occasional candle use in a ventilated home does not approach those exposure thresholds in the literature reviewed. Choose cleaner wax and fragrance, and burn responsibly.

Kristina Braly is a physician and the founder of AEMBR, a clean fragrance and home care brand based in Houston, Texas. AEMBR products are formulated to the standard she set for her own home: no phthalates, no carcinogens, no harsh synthetic chemicals — and nothing she wouldn't burn next to her kids. Shop AEMBR candles.