A hookah is a water pipe used to smoke flavored tobacco. The tobacco, commonly called shisha, is heated with charcoal, and the smoke passes through a water-filled base before being inhaled through a long hose. Hookah has roots in South Asia and the Middle East and is now used worldwide, often in social settings like hookah lounges. Despite a widespread perception that the water filters out harmful substances, hookah smoking carries serious health risks comparable to cigarette smoking.
How a Hookah Works
A hookah has four main parts: the head (or bowl), the body (a vertical stem), the water base, and the hose. Flavored tobacco is packed into the head, and burning charcoal sits on top, usually separated by a layer of foil or a metal screen. When you inhale through the mouthpiece at the end of the hose, you create suction that pulls hot air from the charcoal down through the tobacco. This heats the tobacco enough to produce a thick, flavored aerosol.
The smoke travels down through the body stem and bubbles up through the water in the base. The water cools the smoke, making it feel smoother on the throat, which is one reason people assume it’s safer than cigarettes. From the water, the smoke passes through the hose to the user. A typical session lasts 30 to 60 minutes, and in that time, users inhale 100 to 200 times more smoke by volume than they would from a single cigarette.
What’s in Shisha Tobacco
Shisha is not plain tobacco. It’s a mixture of four main ingredients: tobacco leaf, vegetable glycerin, molasses or honey, and food-grade flavorings. The tobacco leaf provides the nicotine. Virginia flue-cured leaf is the most common type, used in lighter “blonde” shisha, while burley air-cured leaf is standard in darker varieties. Vegetable glycerin, a sugar alcohol derived from plant oils like coconut or soy, is what produces the thick clouds of smoke. Molasses or honey acts as a binder, holding the mixture together and adding sweetness. The flavorings are typically the same kind of food-grade concentrates used in the food industry, suspended in propylene glycol or alcohol.
Herbal, tobacco-free shisha also exists, replacing the tobacco leaf with sugarcane fiber or tea leaves. These products still use glycerin, molasses, and flavorings, so the smoke still contains many of the same combustion byproducts, just without nicotine from tobacco.
Chemicals in Hookah Smoke
The combination of burning charcoal and heated tobacco produces a complex mix of harmful substances. The charcoal alone generates concentrated carbon-rich nanoparticles that are roughly ten times smaller than the particles in cigarette smoke, which may make them more damaging to blood vessels. Charcoal combustion also releases large amounts of carbon monoxide.
Hookah smoke contains heavy metals including arsenic, cadmium, chromium, lead, nickel, and mercury. Cadmium is a known carcinogen that can damage kidneys and bones. Nickel and chromium are also carcinogenic and can cause DNA mutations, lung inflammation, and skin reactions. Significant percentages of these metals transfer from the raw tobacco into the smoke that reaches the user, meaning the water filtration does not effectively remove them.
Carbon monoxide exposure is particularly concerning. Case reports of hookah users have documented blood levels of carboxyhemoglobin (a marker of CO in the blood) ranging from 15% to nearly 34%, with the highest cases requiring emergency treatment. For context, nonsmokers typically have levels below 3%. Exhaled carbon monoxide is significantly higher after a charcoal-heated hookah session compared to electronic hookah devices, confirming that charcoal is a major source of CO exposure.
Effects on the Lungs
Regular hookah use damages lung function in ways that mirror deep-inhalation cigarette smoking. In studies comparing hookah smokers to nonsmokers, hookah users showed significantly lower scores on standard breathing tests. Their predicted lung capacity measured around 77% of what it should be, compared to 97% in non-users. The ratio of air they could force out in one second relative to their total lung capacity dropped from about 90% in nonsmokers to 71% in hookah users, a meaningful decline.
About 10% of hookah smokers in one study met the clinical criteria for chronic obstructive pulmonary disease (COPD). The risk increased with age, years of use, and smoking three or more sessions per day. Chronic cough, excess mucus production, and shortness of breath lasting two or more years were all more common in regular users. At the tissue level, chronic hookah exposure has been linked to DNA damage in the lungs and enlargement of the air sacs where oxygen exchange happens, a hallmark of emphysema.
Infection Risk From Sharing
Hookah is almost always a group activity, and sharing the hose creates a direct route for transmitting infections. Bacteria including Staphylococcus aureus, E. coli, Pseudomonas, Klebsiella, and Streptococcus have all been found on hookah components in surveys of restaurants and cafes. The warm, moist environment inside the water base is also hospitable to fungi.
The list of infections linked to shared water pipes is long. A cluster of tuberculosis cases in Australia was traced to hookah sharing among a group of young adults. The bacterium that causes stomach ulcers, Helicobacter pylori, has been connected to hookah use. Aspergillus, a fungus that can cause serious lung infections, has been isolated from water pipes. Hepatitis C transmission has been associated with shared mouthpieces. More recently, researchers have flagged hookah sharing as a risk factor for respiratory viruses including MERS and SARS-CoV-2. Disposable mouthpiece tips reduce but do not eliminate these risks, since the hose, water, and base remain shared.
Air Quality in Hookah Lounges
Even if you’re not smoking, sitting in a hookah lounge means breathing secondhand smoke. A study measuring fine particulate matter (PM2.5) in all ten indoor hookah lounges operating in Oregon found that none had “good” air quality by EPA standards. Four had air rated “unhealthy,” four were “very unhealthy,” and two reached “hazardous.” The worst lounge had particulate concentrations 50 times higher than the EPA’s threshold for good air quality. These are the same fine particles that penetrate deep into the lungs and enter the bloodstream, posing risks for heart and lung disease even with brief exposure.
Electronic Hookah Devices
Electronic hookahs replace the charcoal with an electric heating element. An e-bowl containing flavored liquid sits on top of a traditional water pipe base. When you inhale, a pressure sensor activates the heating coil, which atomizes the liquid into an aerosol that passes through the water before reaching you. The experience feels similar to traditional hookah, but the chemistry is different.
Because there’s no charcoal combustion, electronic hookahs produce far less carbon monoxide. However, they deliver comparable amounts of nicotine, with plasma nicotine levels after a session nearly identical between the two types (about 5 to 6 nanograms per milliliter). The aerosol from electronic hookahs still contains nanoparticles and free radicals that can trigger inflammation, oxidative stress, and arterial stiffness. Removing charcoal eliminates one major source of toxicants but does not make the device safe.
How Hookah Is Regulated
In the United States, the FDA has regulated hookah tobacco since 2016 under its authority over all tobacco products. This covers manufacturing, importing, packaging, labeling, advertising, and sales. Regulated components include not just the tobacco itself but also flavor enhancers, hose cooling attachments, water filtration additives, charcoal (whether wood, coconut shell, or electric), and physical parts like bowls, valves, and hoses. It is illegal to sell hookah tobacco or any tobacco product to anyone under 21. State and local laws may add further restrictions, particularly around indoor smoking in hookah lounges.