Vapes CannabisNL Concern is growing about synthetic cannabinoids found in THC vapes stronger, riskier, and unpredictable. These substances sometimes called fake weed have been linked to seizures, paranoia and even XVapes Social Dispensary Do you know what's in your THC vape? THC vapes are increasingly being shown by testing to contain synthetic substances with increased risk including unexpected effects due to differences in strength.