Thumbprinting is the practice of pressing your thumb into LSD powder/crystals and then taking that dose. Thumbprinting LSD usually means consuming a very large dose—a dose that is large enough to make you potentially trip for weeks (and some anecdotes suggest you might not recover from a thumbprint).
Thumbprinting is sometimes regarded as an initiation ceremony for groups that revere or distribute LSD. Individuals report some pretty wild experiences from taking such large thumbprint doses of LSD. Some claim that the experience is intensely spiritual. Others claim that the experience of thumbprinting ruined their enjoyment of psychedelics forever.
Still others report that after thumbprinting, they were left with permanent visual snow. This is where your vision is permanently and consistently obscured by static-like flickering dots. These dots can be white, red, or green. Visual snow is associated with hallucinogen persisting perception disorder (HPPD).
What is HPPD?
Hallucinogen persisting perception disorder, or HPPD, is a condition where you continue to experience hallucinogenic flashbacks well after you’ve taken a psychedelic drug.
HPPD is not believed to be common. HPPD can occur after just one interaction with a hallucinogen, or after years of use. HPPD is thought to be associated with dangerous practices such as thumbprinting.