1. Nicotine might stimulate you immediately but overall in the long run causes fatigue and disrupts sleep and circadian rhythm because it disrupts mitochondrial function (ie. the function of the powerhouses in every cell where energy is produced).
2. Nicotine does not relieve stress, in fact it increases anxiety, raises adrenaline and increases your heart rate.
3. Studies have shown that nicotine impairs the way chemotherapy works in lung cancer because anti cancer drugs rely on pathways of programmed cell death to destroy tumours but nicotine prevents the mitochondria in cells stimulating cell death thereby leading to tumours getting bigger and becoming resistant to therapy. So don't think it's too late to give up smoking if you have been diagnosed with cancer. Quitting now might make all the difference in your recovery.
4. All forms of nicotine are harmful to the development of the brains/central nervous systems in foetuses. Exposure to smoking during pregnancy can lead to behavioural problems eg. ADHD and intellectual deficits in their developing children.
5. Nicotine reduces blood flow to the penis and can hence lead to erectile dysfunction.
6. Nicotine has an impact on ability to conceive in both men and women.
In women nicotine has been shown in research to reduce fertility by leading to an increased loss of eggs, impaired quality of eggs and damage to the ovaries. Nicotine in vaping liquids has been shown in research to affect the quality of sperm.