Nausea

Nausea can be described as an uncomfortable sensation of unease and discomfort in the upper stomach accompanied by an involuntary urge to vomit. This effect is one of the most commonly reported negative physical side effects across virtually all classes of psychoactive substances. It typically manifests as a queasy, unsettled feeling in the stomach that may be accompanied by increased salivation, slight dizziness, and a general sense of physical malaise.

The intensity and duration of substance-induced nausea varies considerably depending on the compound, dosage, route of administration, and individual physiology. In many cases, nausea is most pronounced during the onset or come-up phase of the experience and gradually subsides as the peak effects establish themselves. For some substances, the nausea may pass once the user has vomited, while for others it can persist throughout the duration of the experience as a persistent background discomfort.

Among psychedelics, nausea is particularly common with psilocybin mushrooms, ayahuasca, mescaline-containing cacti, and various phenethylamine psychedelics such as 2C-B and the DOx series. With mushrooms, the nausea is partly attributed to the chitin in the fungal cell walls and can be significantly reduced by consuming them on an empty stomach, making a tea, or using lemon tek preparation methods. With ayahuasca, purging (vomiting) is considered a traditional and expected part of the ceremonial experience.

Opioids are also notorious for inducing nausea, particularly in opioid-naive individuals or when doses are escalated. This occurs through direct stimulation of the chemoreceptor trigger zone in the brainstem. Stimulants, dissociatives, deliriants, and even some GABAergic depressants can produce nausea as well, though the mechanisms and typical severity vary between substance classes.

Nausea is often accompanied by other coinciding effects such as stomach bloating, stomach cramps, dizziness, and temperature regulation suppression. Common harm reduction strategies for managing substance-induced nausea include fasting for several hours before ingestion, consuming ginger tea or supplements, using antiemetic medications such as ondansetron, and remaining in a comfortable position. For many users, nausea is a transient inconvenience that passes within the first hour, while for others it can significantly diminish the quality of an otherwise positive experience.