The 4mg gum is for smokers of more than 20 cigarettes a day. Nicorette can also be used to relieve cravings while in areas you cannot some such as planes or in the cinema.
20 cigarettes or fewer: One 2 mg Gum as required to relieve cravings.
More than 20 cigarettes: One 4 mg Gum as required to relieve cravings.
The Nicorette Chewing Technique
1. Chew slowly until taste becomes strong.
2. Rest between gum and cheek.
3. Chew again when the taste has faded. Keep chewing like this for about half an hour. After this time the gum will have lost its strength and you should dispose of it carefully.
4 milligrams (mg) of nicotine.