Purpose: Acute nicotine poisoning by liquid nicotine in electronic cigarettes is becoming an increasing problem worldwide. The current systematic review aimed to determine the harm of acute nicotine poisoning by reviewing published case reports. Methods: An online literature search with PubMed, Embase, Cochrane Library, and KoreaMed database was performed to identify relevant studies addressing acute nicotine poisoning with electronic cigarettes. Two investigators searched the case reports written in English or Korean. Results: Twenty-six cases were included in this study. The routes of intoxication included ingestion in 18 cases, intravenous injection in three cases, subcutaneous injection in two cases, and ocular exposure in two cases. Ten cases had a cardiac arrest, and seven of them died. Seven out of 12 cases with intentional poisoning had a cardiac arrest. Nine children under 18 years were reported, and three of them had a cardiac arrest. Sixteen cases without a cardiac arrest recovered well, except for one case with sudden sensorineural hearing loss. Conclusion: The authors reviewed the risks of electronic cigarette liquid in terms of acute poisoning through a systematic review. The nicotine solution of an e-cigarette can be life-threatening in cases of acute poisoning. Therefore, active emergency treatment with early recognition is necessary. In addition, various management methods and regulations for preventing acute nicotine poisoning, such as restriction of distribution and nicotine concentration, should be considered.