1P-LSD (1-propanoyl-lysergic acid diethylamide) is a psychedelic drug of the lysergamide class that is a derivative and functional analogue of LSD and a homologue of ALD-52. It originated in 2015 when it appeared a designer drug sold online.

1P-LSD is a semi-synthetic compound that is derived from lysergic acid. This substance is considered to be a potent agonist of the 5HT2A receptor. 1P-LSD is also similar in structure to LSD, which is why it is sometimes referred to as "mini-LSD" or "microdosing LSD."