Doctors are warning about a substance they call gas station heroin that is available over the counter at vape stores across Arizona. The product is called 7 OH, a component derived from kratom. Pseudoindoxyl Vape 7rx Pseudo 7OH Kratom Extract Tablets 90mg 3ct (30mg tab Is Pseudoindoxyl Legal Australia Operation Vape Trail' cracks down on synthetic marijuana, 7 OH, kratom, more What Is a 7 OH Vape? Safety, Legality & Alternatives Parents: Have You Heard of 7 OH? A new substance called 7 OH ( 7 Hydroxymitragynine) is starting to appear in gas stations, vape shops, and online stores, and many people don't realize the risks.