People smoke tobacco more than anything else, with 1.2 billion users worldwide as of 2024. But tobacco is far from the only substance that gets lit up and inhaled. Cannabis, hookah, e-cigarettes, herbal blends, clove cigarettes, and illicit drugs round out the list. Here’s what each involves and why smoking remains so common despite well-known risks.
Tobacco: The Most Common Smoked Substance
Roughly one in five adults globally still uses tobacco, despite decades of public health campaigns. The numbers have dropped from 1.38 billion users in 2000 to 1.2 billion in 2024, but tobacco remains deeply embedded in daily life across every continent. Europe now has the highest regional prevalence at 24.1% of adults, followed by the Western Pacific at 22.9%. Africa has the lowest at 9.5%.
More than four out of five tobacco users are men, with close to 1 billion men using tobacco worldwide. Female tobacco use has fallen to 6.6% globally, though women in Europe buck that trend with the highest female prevalence of any region at 17.4%.
Tobacco is smoked in several forms. Manufactured cigarettes are the most popular, but hand-rolled cigarettes, cigars, cigarillos, pipe tobacco, and bidis (thin, hand-rolled cigarettes common in South Asia) all have significant user bases. What makes tobacco uniquely habit-forming is nicotine’s speed: after a single puff, nicotine reaches half its peak concentration in the brain within about 25 seconds. That near-instant hit to the brain’s reward system is what keeps people coming back.
E-Cigarettes and Vaping
E-cigarettes don’t technically involve combustion, but most users describe the experience as smoking and the devices deliver nicotine through inhaled vapor. More than 100 million people worldwide now vape, including at least 86 million adults and an estimated 15 million adolescents aged 13 to 15.
In the United States, adult e-cigarette use rose from 4.5% in 2019 to 6.5% in 2023. Young adults aged 21 to 24 are the heaviest users at 15.5%, outpacing even 18-to-20-year-olds at 10.3%. Men vape at higher rates than women (7.6% vs. 5.5% in 2023), though the gap has narrowed. E-cigarettes heat a liquid containing nicotine, flavorings, and a carrier base (typically propylene glycol or vegetable glycerin) into an aerosol. The nicotine reaches the brain just as fast as it does from a traditional cigarette, about 27 seconds to half-peak concentration.
Cannabis
Cannabis is the second most commonly smoked plant material worldwide. In the United States, about 15.3% of adults reported current marijuana use in a 2022 survey, and smoking was by far the preferred method. Nearly 80% of users reported smoking cannabis at least sometimes, and 62.4% said smoking was their primary route. Vaping cannabis came in second at 16.8%, followed by edibles at 14.2% and dabbing (inhaling heated concentrates) at 14.6%.
Cannabis is typically smoked in joints (rolled in paper), blunts (rolled in tobacco leaf wraps), glass or water pipes, and small hand pipes. The active compounds, primarily THC, are absorbed through the lungs and reach the bloodstream within seconds, producing effects much faster than edibles, which can take 30 minutes to two hours.
Hookah and Shisha
Hookah, also called shisha or waterpipe, involves heating flavored tobacco with charcoal and pulling the smoke through water before inhaling it. It’s especially popular in the Eastern Mediterranean, South Asia, and increasingly among young adults in Western countries who treat it as a social activity.
A common misconception is that the water filters out harmful substances. It doesn’t, at least not meaningfully. Hookah smoke contains nicotine, tar, carbon monoxide, ultrafine particles, and volatile organic compounds. The charcoal is actually the bigger problem: research has found that 90% of the carbon monoxide and 95% of the cancer-linked polycyclic aromatic hydrocarbons in hookah smoke come from charcoal combustion, not the tobacco itself. Charcoal smoke also contains heavy metals like lead, zinc, and iron at concentrations similar to or higher than those in cigarettes. A typical hookah session lasts 45 to 60 minutes, meaning total smoke exposure in a single sitting can far exceed that of a cigarette.
Clove Cigarettes
Clove cigarettes, known as kreteks, originated in Indonesia and remain widely used across Southeast Asia. They contain a blend of tobacco and ground clove buds, plus a flavoring “sauce” that varies by manufacturer. Burning clove buds release high levels of eugenol, a compound with mild numbing properties. This can make the smoke feel smoother and less harsh on the throat, which may encourage deeper or longer inhalation. Kreteks carry the same risks as regular cigarettes, with the added concern that the anesthetic effect of eugenol can mask early signs of airway irritation.
Herbal Cigarettes
Herbal cigarettes contain no tobacco or nicotine. They’re made from dried plant material and are sometimes marketed as a “natural” or safer alternative. Common ingredients include mullein, marshmallow leaf, damiana, passion flower, ginseng, green tea, mugwort, clove, lavender, peppermint, and thyme. Some brands add vanilla, cherry, or jasmine for flavor.
The fact that they’re nicotine-free doesn’t make them harmless. Burning any plant material produces tar, carbon monoxide, and particulate matter. Herbal cigarettes generate many of the same combustion byproducts as tobacco cigarettes. They’re sometimes used by actors on film sets or by people trying to quit nicotine while maintaining the physical ritual of smoking, but they still expose the lungs to irritants.
Illicit Substances
Several illegal drugs are commonly smoked or inhaled through heated vapor. Crack cocaine is smoked in glass pipes, producing a rapid, intense high that lasts only a few minutes. Methamphetamine is often smoked in a similar way, using a glass pipe to heat the crystallized form into vapor. Freebase heroin can be smoked by heating it on foil and inhaling the fumes, a method sometimes called “chasing the dragon.” Synthetic cannabinoids (often sold as “Spice” or “K2”) are sprayed onto dried plant material and smoked like cannabis, though their chemical composition and potency are unpredictable and frequently dangerous.
The appeal of smoking these substances is the same mechanism that makes nicotine so addictive: the lungs provide an enormous surface area for absorption, sending compounds to the brain in seconds. This rapid delivery intensifies the high but also accelerates dependence.
Why Smoking Persists
The reason people smoke so many different substances comes down to biology. The lungs contain roughly 300 million tiny air sacs that provide a direct route into the bloodstream. Inhaled substances bypass the digestive system entirely, reaching the brain faster than almost any other delivery method short of injection. For nicotine specifically, that 25-second trip from lungs to brain creates a tight loop between the act of puffing and the feeling of reward, reinforcing the habit hundreds of times a day for a pack-a-day smoker.
Tobacco alone causes over 8 million deaths globally each year. Many countries have responded with flavor bans to reduce the appeal of smoking, particularly among young people. The United States banned flavored cigarettes (except menthol) in 2009. The European Union prohibited menthol and other characterizing flavors in cigarettes by 2020. Canada, Turkey, and several African and Asian nations have enacted similar restrictions. Despite these measures, the sheer variety of smokable substances and the speed of lung-based delivery ensure that smoking in some form remains one of the most widespread drug habits on the planet.