Cigarettes contain nicotine, which is highly addictive.
Even if you want to quit smoking, you may find it difficult because you're addicted to the effects of nicotine.
Chemicals in your brain
Nicotine alters the balance of 2 chemicals called dopamine and noradrenaline in your brain.
When nicotine changes the levels of these chemicals, your mood and concentration levels change. Many smokers find this enjoyable.
The changes happen very quickly. When you inhale the nicotine, it immediately rushes to your brain, where it produces feelings of pleasure and reduces stress and anxiety.
This is why many smokers enjoy the nicotine rush and become dependent on it.
The more you smoke, the more your brain becomes used to the nicotine.
This means you have to smoke more to get the same effect.
Effects of quitting smoking
When you stop smoking, the loss of nicotine changes the levels of dopamine and noradrenaline.
This can make you feel anxious, depressed and irritable.
It's normal to crave nicotine when you quit, as smoking provides an immediate fix to these unpleasant feelings.
Getting help to quit
Nicotine cravings can be very strong, making it difficult to quit using just your willpower.
If you want to stop smoking, see your GP, who can refer you to an NHS Stop Smoking support service.
These services offer the best support for people who want to give up smoking.
Studies show that you're up to 4 times more likely to quit smoking if you do it through the NHS.
NHS Stop Smoking programmes can provide stop smoking treatments like nicotine patches and gum, or medicine treatments, to help you stop smoking for free on prescription.
They also provide counselling, support and advice.
Find your nearest NHS Stop Smoking service on the NHS Smokefree website or call the Smokefree national helpline on 0300 123 1044 (England only) to speak to a trained adviser.
If you don't want to be referred to an NHS Stop Smoking support service, your GP can still provide treatment, support and advice to help you quit smoking.
Read the answers to more questions about stopping smoking.
Page last reviewed: 26 September 2018
Next review due: 26 September 2021