Crack injecting is more dangerous to the veins and local tissues than injecting heroin because people inject it more often, it has a local anaesthetic effect and because the solution is often very acidic (because too much has been added to get the drug to dissolve) and therefore causes significant additional vein damage.

The harm reduction works 'crack wastes veins' poster that conveys this risk, and encourages crack and speedball users towards stopping, or using less dangerous routes of administration.