Coughing after using a cannabis vape is a common reaction. This strong reflex results from multiple factors related to the chemical composition of the oil and the physics of how the vapor is delivered. The intense, involuntary cough is a natural protective mechanism, signaling that the airways are encountering foreign materials or conditions they perceive as damaging. Understanding the specific causes, which range from the cartridge ingredients to the device temperature, is the first step toward a more comfortable experience.
Chemical Irritants in the Vape Oil
The liquid within a cannabis vape cartridge is a complex chemical mixture that is a primary source of airway irritation. Beyond the cannabinoids, various additives and breakdown products can directly stimulate cough receptors in the throat and lungs. These receptors, particularly the highly sensitive TRPA1 and TRPV1 channels in the airway lining, react strongly to certain chemical compounds.
Many cartridges contain thinning agents, such as Propylene Glycol (PG) or Vegetable Glycerin (VG), used to adjust the oil’s viscosity. While safe for ingestion, inhaling these compounds in aerosol form is different. When heated, PG and VG can thermally degrade into aldehydes, including formaldehyde and acetaldehyde. These compounds are known respiratory irritants and can trigger inflammation and the cough reflex.
Terpenes, the natural compounds that give cannabis its distinct aroma and flavor, also contribute significantly to the harshness of the vapor. Highly concentrated or isolated terpenes, often added back into the oil after extraction, are powerful irritants when heated. For example, terpenes like pinene and myrcene can degrade into acrolein at high temperatures. Acrolein is a pungent chemical that activates the same sensory channels as capsaicin, the active component in chili peppers.
The quality of the vape oil is another consideration, as poor manufacturing can introduce dangerous contaminants. Illicit or low-quality cartridges have previously contained severe additives like Vitamin E acetate, which was strongly linked to e-cigarette, or vaping, product use-associated lung injury (EVALI). Even trace amounts of pesticide residues or heavy metals leached from the heating element can become airborne. These contaminants contribute to irritation and stimulate a toxic response in the lungs, as the body reacts to foreign substances it is not equipped to process.
Physical Factors of Vapor Delivery
Beyond the chemical makeup of the oil, the physical properties of the vapor activate the body’s protective cough reflex. The vapor’s temperature, moisture content, and the size of its microscopic particles all contribute to mechanical irritation of the respiratory tract. These factors combine to make vaping a unique physical experience for the lungs, distinct from traditional smoke inhalation.
The high temperature generated by the heating coil is a major factor, as the vapor delivered to the airways is often significantly hotter than ambient air. While a device may be set to a specific temperature, localized hotspots within the coil can exceed 250°C, creating thermal stress. The TRPV1 receptors in the throat and lungs are designed to detect heat and chemical irritants. They trigger a rapid cough as a defense mechanism against potential thermal damage.
Vapor, or aerosol, lacks the moisture content of ambient air, resulting in a rapid drying effect on the delicate lining of the mouth and throat. This dehydration of the airway tissue, particularly the trachea, is a direct mechanical stimulus for the cough receptors. The absence of moisture causes immediate discomfort, prompting the body to react by attempting to clear the perceived obstruction or irritant.
Furthermore, the vapor consists of ultrafine aerosol particles, which are microscopic droplets of oil and condensed compounds. These particles are often small enough (less than five micrometers in aerodynamic diameter) to penetrate deeply into the lower respiratory tract, reaching the sensitive bronchioles and alveoli. Particles in this size range bypass the upper airway’s defense mechanisms. They deposit in the deepest parts of the lungs, where they cause irritation and inflammation, triggering a cough as the body tries to expel them.
Controlling the Cough: Technique and Device Management
Users can take several direct steps to mitigate harshness and reduce coughing by adjusting their inhalation technique and device settings. These adjustments address chemical and physical irritants before they reach the most sensitive parts of the airway.
A fundamental change involves adopting a slower, shorter inhalation technique, often called a mouth-to-lung draw. Instead of a long, deep pull directly into the lungs, take a gentle puff into the mouth first. This allows the hot vapor to cool before it is inhaled into the throat and lungs. This cooling minimizes the thermal shock that triggers heat-sensitive cough receptors, making the experience smoother.
It is beneficial to avoid holding the vapor in the lungs for an extended period. Most desired compounds, such as THC, are absorbed into the bloodstream within the first few seconds of contact with the alveoli. Prolonged breath-holding only increases the contact time between the airway tissue and the hot, chemically active vapor, amplifying irritation and the likelihood of a reactive cough.
Optimizing the device’s temperature settings is an effective measure, especially with batteries that offer variable voltage or wattage control. Lowering the temperature to a moderate range, such as 180–190°C (356–374°F), significantly reduces the thermal degradation of thinning agents and terpenes into harsh chemical irritants like acrolein. Using the lowest setting that still produces the desired effect ensures a cleaner, less irritating vapor.
Maintaining proper hydration helps counteract the drying effect of the vapor on the respiratory tract. Drinking water before and during a vaping session keeps the airway lining moist, making it less susceptible to the immediate dehydration that activates the cough reflex. Regularly cleaning the device and replacing burnt or old coils prevents the inhalation of foul-tasting residue and partially combusted oil, which generate an extremely harsh and irritating vapor.