[尼古丁 NICOTINE] A highly addictive substance that may lead to excessive use and eventually, nicotine poisoning. Nicotine is present in a concentrated form within e-liquid from vapes and refill packs. Here are some harmful effects of nicotine: Nicotine poisoning Symptoms include: Vomiting Sweating Dizziness Increased heart rate Lethargy Seizures Difficulties in breathing