What Chemicals and Additives Do Cigars Have in Them?

Cigars contain a complex mix of naturally occurring compounds, fermentation byproducts, and intentionally added substances that together produce hundreds of chemicals, many of them toxic or carcinogenic. Unlike cigarettes, which are often assumed to be more chemically processed, cigars carry their own distinct chemical profile shaped by the tobacco varieties used, the long fermentation process unique to cigar production, and whatever humectants or flavorings the manufacturer applies. The result is a product whose chemistry is more layered than most cigar smokers realize.

What Is Already in the Tobacco Leaf

Before any manufacturing step, cigar tobacco leaves are packed with naturally occurring chemicals. The most prominent group is the alkaloids, with nicotine being the dominant one. Cigar tobaccos tend to use air-cured or sun-cured leaf varieties, which have somewhat different alkaloid profiles than the flue-cured tobacco common in cigarettes. Research measuring the four primary alkaloids in tobacco (nicotine, anatabine, nornicotine, and anabasine) found that their combined concentration varies by curing method, with flue-cured leaf containing about 62% total alkaloids in its extract compared to roughly 51% for burley tobacco, a variety often used in cigar blends.¹ While nicotine gets all the attention, these other alkaloids matter because some of them serve as chemical precursors. Nornicotine, for instance, can be converted into potent carcinogens during fermentation and combustion.

Beyond alkaloids, raw cigar tobacco leaves contain sugars, starches, proteins, cellulose, lignin, pectin, and polyphenols. These compounds are not inert bystanders. They are the raw material that fermentation and, later, combustion transform into the chemicals you actually inhale. A cigar’s flavor, aroma, and toxicity all trace back, in part, to the starting chemistry of the leaf itself.

How Fermentation Reshapes the Chemistry

Cigar production involves a prolonged fermentation stage that cigarettes skip entirely. After harvesting and initial curing, cigar leaves are stacked in large piles called pilones, where microbial activity and heat drive chemical transformations over weeks or months. This step is what gives cigars their characteristic flavor complexity, but it also creates and concentrates several harmful chemicals.

During fermentation, the leaf’s composition changes dramatically. The contents of total sugar, reducing sugar, starch, cellulose, lignin, pectin, polyphenols, and protein all drop significantly as microbes break them down.² At the same time, fermentation increases nitrogenous heterocyclic compounds, certain sugars, alkaloids, and organic acids, all of which contribute to the finished cigar’s flavor and smoke chemistry.³

The most troubling byproducts of fermentation are tobacco-specific nitrosamines, commonly referred to as TSNAs. These are potent carcinogens, and cigar tobacco generates particularly high levels of them during fermentation. The two most studied TSNAs are NNN and NNK, both classified as human carcinogens. The fermentation conditions that cigars require, particularly the sustained heat in the pilones, create an environment where nitrosamine formation accelerates.⁴ Researchers have been exploring ways to reduce TSNAs during cigar fermentation, including introducing specific bacteria that can cut total TSNA content by around 60%.⁵ That research underscores both how significant the TSNA problem is in cigar production and how far the industry is from solving it at scale.

Intentionally Added Chemicals

Beyond what forms naturally or through fermentation, cigar manufacturers add several categories of chemicals during production.

Humectants

Humectants are moisture-retention agents added to keep tobacco pliable and prevent it from drying out and crumbling. The two most widely used humectants in the tobacco industry are glycerol and 1,2-propylene glycol, often present in tobacco products at roughly 2 to 5 percent by weight.⁶ Propylene glycol, in particular, is one of the most utilized humectants across various tobacco product types, including cigars.⁷ Both glycerol and propylene glycol are considered safe for food use, but that designation refers to ingestion, not inhalation of their combustion and thermal-decomposition products. When these substances burn in a cigar, they can break down into aldehydes and other irritants.

Flavorings and Casing Agents

Many cigars, and especially little cigars and cigarillos, are flavored. The flavoring chemicals involved are more numerous and more concerning than most consumers expect. An analysis of commercially available little cigar products identified 66 individual flavorant compounds across the brands tested, with each brand containing anywhere from 4 to 24 distinct flavoring chemicals.⁸ These include compounds responsible for familiar tastes like strawberry, vanilla, chocolate, and grape. Casing agents, which are sugar-based or cocoa-based solutions applied to the tobacco before rolling, serve a similar purpose by sweetening and smoothing the smoke.

The concern with flavorings goes beyond the flavoring chemicals themselves. When burned, they interact with the tobacco matrix to generate additional toxic byproducts. That same study on little cigars found a strong correlation between the number of flavorants in a product and the amount of toxic free radicals in its smoke. Products containing ethyl methylphenylglycidate, a strawberry-flavor compound, produced more than twice the levels of certain radical species compared to less flavored products.⁸ In other words, the more flavorings in the cigar, the more harmful the smoke tends to be.

Ammonia Compounds

Some tobacco products use ammonia or ammonium compounds during processing. Ammonia increases the alkalinity of tobacco smoke, which shifts the chemical equilibrium so that a greater proportion of nicotine exists in its free-base form rather than as a bound salt. Free-base nicotine is more volatile and more readily absorbed through the airways.⁹ This effect has been studied primarily in the context of cigarettes, but the same chemistry applies to any tobacco smoke with elevated pH. Cigar smoke is naturally more alkaline than cigarette smoke, which is one reason cigar nicotine absorbs efficiently through the mouth lining even without inhalation.

Heavy Metals in Cigar Tobacco

Tobacco plants are efficient at pulling metals out of the soil, and cigar tobacco is no exception. A review of heavy metal content in cigars found a wide range of elements present in measurable quantities. Iron and manganese were the most abundant, with iron concentrations ranging from 420 to 2,200 micrograms per gram of tobacco and manganese from 100 to 370 micrograms per gram. Zinc, copper, lead, cadmium, nickel, chromium, cobalt, arsenic, and mercury were all detected as well, though at lower concentrations.¹⁰

The ranges are strikingly wide, which reflects differences in where the tobacco was grown, the soil composition, local agricultural practices, and the cigar type. Lead, for example, was undetectable in some products and as high as 32 micrograms per gram in others. Cadmium, which is particularly toxic to the kidneys and is a known carcinogen, ranged from undetectable to 19 micrograms per gram.¹⁰ When these metals are present in the tobacco, a fraction of them transfers into the smoke and can be inhaled or absorbed through the oral mucosa. Because cigars use substantially more tobacco per unit than a cigarette, total metal exposure from a single cigar session can be considerable.

What Happens When You Light Up

Combustion transforms everything discussed so far into a far more complex mixture. The smoke from a burning cigar contains thousands of chemical compounds, many of them generated in the moment the tobacco ignites rather than being present in the unburned leaf.

Cigar smoke is a major source of carbon monoxide and fine particulate matter. Controlled experiments measuring indoor air during cigar smoking found that a single cigar produces more total carbon monoxide than a single cigarette, and that average CO concentrations at cigar social events were comparable to or higher than levels measured on a freeway during rush-hour traffic.¹¹ Total emissions of respirable suspended particles and particle-bound polycyclic aromatic hydrocarbons also exceed those of a single cigarette, mainly because a cigar is larger and burns for a longer time.¹¹ This is an important distinction: gram for gram, cigar tobacco may produce slightly fewer particles than cigarette tobacco, but a typical cigar contains far more tobacco, so the total exposure per smoking session is greater.

Cigar smoke also contains higher concentrations of several toxic and carcinogenic compounds compared to cigarette smoke.¹² Among the most concerning are volatile organic compounds. Research on little cigars identified five key VOCs in mainstream smoke: 1,3-butadiene, acrylonitrile, benzene, isoprene, and toluene. These ranged from microgram to milligram quantities per cigar.¹³ Benzene and 1,3-butadiene are both classified as known human carcinogens; acrylonitrile is a probable one.

Little Cigars and Cigarillos vs. Premium Cigars

Not all cigar products are chemically equivalent. The category spans everything from large, hand-rolled premium cigars to mass-produced little cigars that look and smoke much like cigarettes. The chemical differences between these product types matter.

Studies comparing cigarillos and little cigars under realistic smoking conditions found that cigarillos delivered more total toxicants across the board, including both volatile and semi-volatile organic compounds, than little cigars or cigarettes. Little cigars produced about the same absolute amount of toxicants as cigarettes. However, when adjusted for the amount of tobacco actually burned, little cigar smoke contained more nicotine, more TSNAs, and more of certain VOCs like acetonitrile and acrylonitrile than cigarillo smoke did.¹⁴ The variation in exposure between individual cigarillo smokers was also much larger than among little cigar smokers, likely reflecting differences in puff behavior and product construction.¹⁵

For premium cigar users, biomarker data from a large national survey showed that even exclusive premium cigar smokers had significantly elevated internal exposure to multiple harmful chemicals compared to non-tobacco users. Their levels of cotinine (a nicotine breakdown product) were roughly 12 times higher, the TSNA metabolite NNAL was about 6 times higher, and a metabolite of acrylonitrile was about 3 times higher than in non-users.¹⁶ The idea that premium cigars, because they are “pure tobacco” with fewer additives, pose minimal chemical exposure simply does not hold up when you measure what actually ends up in the body.

Microbial Hitchhikers and Their Byproducts

Cigars are not sterile products. The fermentation process that is so central to cigar production relies on microbial activity, and not all of those microbes disappear from the finished product. Research characterizing the microbiomes of commercially available tobacco products has identified over 89 unique bacterial genera and 19 fungal genera across cigarettes, cigars, cigarillos, hookah, and smokeless tobacco. The most common bacteria found include Bacillus, Pseudomonas, and Staphylococcus. Fungal genera include Aspergillus, Penicillium, Mucor, and Candida, among others.

Some of these organisms are capable of producing mycotoxins or endotoxins. Aspergillus species, for example, can generate aflatoxins, which are among the most potent naturally occurring carcinogens known. Whether the levels present on a finished cigar are high enough to contribute meaningfully to health risk on top of everything else in cigar smoke is an open question, but the presence of these organisms is well documented. For people with compromised immune systems, even the act of handling unlit cigars could conceivably introduce opportunistic pathogens.

What Biomarker Studies Confirm

All the chemistry discussed above would be academic if these substances were not actually making it into the smoker’s body. Biomarker studies settle that question definitively. The PATH (Population Assessment of Tobacco and Health) Study measured exposure biomarkers in U.S. adult cigar smokers and found elevated levels across every category tested: nicotine and tobacco alkaloids, TSNAs, polycyclic aromatic hydrocarbons, volatile organic compounds, and metals.¹⁷

These findings hold even for cigar smokers who report not inhaling. Because cigar smoke is alkaline, nicotine and many other compounds absorb efficiently through the lining of the mouth and throat. You do not need to pull cigar smoke into your lungs for these chemicals to enter your bloodstream, though inhaling obviously increases the dose. The biomarker evidence makes clear that the chemical exposure from cigar smoking is real, measurable, and spans the full range of harmful compound classes present in the smoke itself.

Why “All-Natural” Claims Are Misleading

Premium cigars are frequently marketed with the implication that they contain only tobacco and nothing else, sometimes carrying explicit “all-natural” labels. This framing invites a dangerous misunderstanding. Many of the most harmful chemicals in cigar smoke are not additives at all. TSNAs form from the tobacco’s own alkaloids during fermentation. Heavy metals are absorbed by the plant from the soil. Polycyclic aromatic hydrocarbons, benzene, carbon monoxide, and formaldehyde are products of combustion that occur when any organic material burns. No amount of purity in sourcing can eliminate these chemicals because they are inherent to what tobacco is and what happens when you set it on fire.

Even the distinction between “additive-free” and “chemically simpler” does not hold. A premium cigar that genuinely contains no added humectants, flavorings, or processing chemicals still delivers TSNAs, heavy metals, VOCs, PAHs, fine particulate matter, and carbon monoxide when smoked. The fermentation process itself, which is essential to making cigar tobacco palatable, is one of the main sources of carcinogen formation. You could start with the purest tobacco leaf imaginable and still end up with a product whose smoke contains dozens of known carcinogens and toxicants, because the chemistry of burning aged plant matter guarantees it.

The Secondhand Smoke Dimension

The chemicals in cigar smoke do not stay confined to the smoker. Because cigars burn for a much longer period than cigarettes and produce a larger volume of sidestream smoke (the smoke that drifts off the lit end between puffs), they are a particularly potent source of indoor air pollution. The same controlled experiments that measured carbon monoxide from cigar smoking found that a single cigar in an enclosed room produced CO levels that could affect bystanders, and that cigar social events generated concentrations rivaling highway traffic.¹¹ Fine particles and polycyclic aromatic hydrocarbons, both of which penetrate deep into the lungs, were also elevated. Anyone sharing a room with a burning cigar is breathing a nontrivial dose of the same chemical mixture the smoker is exposed to, regardless of whether they personally use tobacco.