Nicotine is addictive and can cause side effects such as headache, nausea, or throat irritation. If you experience these symptoms, stop using HEETS and consult a healthcare professional. Nicotine is not the leading cause of tobacco-related diseases. This fact is supported by scientific evidence and many public health officials. - Many authorities have stated that "[i] it is primarily the hazardous substances and carcinogens in tobacco smoke - not nicotine - that cause illness and death." - Nicotine is naturally present in tobacco used in HEETS. - Minors, pregnant or nursing women, and people with heart disease, high blood pressure, or diabetes, however, should not use tobacco products or those containing nicotine.