Injecting substances intravenously or intramuscularly, though practised by some individuals, comes with a unique set of risks that cannot be overlooked. While this route of administration may offer certain advantages in terms of rapid onset or bioavailability for some substances, it also introduces a host of potential dangers to the user's health and safety.

This fact sheet aims to provide comprehensive insights into the general risks associated with injecting drugs, along with harm reduction principles that can mitigate these risks to some extent. Additionally, it addresses specific concerns related to injecting psychedelics, a practice that presents its own set of challenges and considerations.

Hallucinogen Persisting Perception Disorder (HPPD) is the experience of sensory disturbances some time after the consumption of a psychoactive substance.

The phenomenon was initially described in 1954 during research into the clinical application of LSD.

Serotonin syndrome is an immediately life threatening condition that results from an excess of serotonin in the space between the neurons. It usually results from combining multiple drugs that increase serotonin by different mechanisms. Often, a Monoamine Oxidase Inhibitor which decreases the breakdown of serotonin, with another substance that increases the amount of serotonin, such as MDMA or MDA.