Question: I have been chewing Nicorette gum for four years after using it to quit smoking. Can this harm me? I have experienced tingling in my fingers and toes and I’m wondering if this is from nicotine restricting the blood supply to those areas.
Dr. Hibberd’s answer:

Yes. Your question really is about the long-term safety of nicotine ingestion. Nicotine is not a smart diet supplement. Nicotine gum is used to aid in the cessation of cigarette smoking, but it is intended for short-term use, and certainly should not be used for more than 12 months. Let’s set the record straight here for you on nicotine:
• Nicotine is highly addictive and is believed to be the most highly addictive component of many substances found in cigarettes.
• Nicotine stimulates the release of adrenalin (epinephrine), increases your heart rate, causes arterial constriction of peripheral small arteries (hence your tingling in fingers and toes), and removes the protective effect estrogen has on brain structure, especially in the hippocampus in women.
• Nicotine is used as an "organic" pesticide. It kills.
• Small amounts of nicotine are stimulants in humans (and all mammals), but large amounts are toxic and can be deadly.
The sooner you wean off this the better. Seek professional help with this.