The virus can progress through the respiratory tract and into a person’s lungs. This causes inflammation and the air sacs, or alveoli, that can fill with fluid and pus. This progression then limits a person’s ability to take in oxygen.

People with severe cases of pneumonia may have lungs that are so inflamed they cannot take in enough oxygen or expel enough carbon dioxide.

Continuous oxygen deprivation can damage many of the body’s organs, causing kidney failure, heart failure, and other life threatening conditions.

Marijuana smoking is associated with large airway inflammation, increased airway resistance, and lung hyperinflation, and those who smoke marijuana regularly report more symptoms of chronic bronchitis than those who do not smoke.67,68 One study found that people who frequently smoke marijuana had more outpatient medical visits for respiratory problems than those who do not smoke.69 Some case studies have suggested that, because of THC’s immune-suppressing effects, smoking marijuana might increase susceptibility to lung infections, such as pneumonia, in people with immune deficiencies; however, a large AIDS cohort study did not confirm such an association.67 Smoking marijuana may also reduce the respiratory system’s immune response, increasing the likelihood of the person acquiring respiratory infections, including pneumonia.