Increased phlegm production

Increased phlegm production describes a state in which the respiratory tract and throat produce unusually large amounts of thick, viscous mucus that accumulates in the throat and upper airways. The sensation is one of the back of the throat and mouth repeatedly filling with a slime-like substance that needs to be periodically swallowed, spat out, or coughed up to prevent discomfort. While rarely dangerous, the constant need to manage excess phlegm can be distracting and mildly unpleasant.

The mechanism appears to involve parasympathetic activation of mucus-secreting goblet cells and submucosal glands in the respiratory tract. Certain psychoactive substances, particularlytryptamine psychedelics (psilocybin, DMT, ayahuasca), strongly stimulate parasympathetic outflow as part of their broader autonomic effects, leading to increased secretory activity across multiple glandular systems simultaneously. This is why increased phlegm production frequently co-occurs with other parasympathetic manifestations: excessive yawning, watery eyes, runny nose, and increased salivation. This cluster of effects — sometimes called the "tryptamine yawn" complex — is a well-recognized signature of the psilocybin come-up in particular.

The timing of this effect typically aligns with the onset and come-up phases of the experience, when autonomic disruption is at its peak, and tends to diminish as the experience plateaus. The intensity correlates with dose, becoming more pronounced and potentially more uncomfortable at heavy dosages. Some individuals appear to be more susceptible than others, possibly due to baseline differences in parasympathetic tone or mucosal gland sensitivity.

From a practical standpoint, having tissues or a towel nearby during the come-up of a tryptamine experience is a simple but often overlooked preparation. Some users find that staying upright rather than lying down helps manage the phlegm more comfortably. While the effect is ultimately harmless and temporary, it can be particularly unwelcome during experiences where the individual is trying to relax and surrender to the onset.