Therapeutic nicotine, or nicotine replacement therapy (NRT), works by replacing some of the nicotine that smokers get from cigarettes, but without the tar and poisonous chemicals. NRT targets receptors in the brain with sufficient nicotine to overcome the cravings when a person quits smoking. Using NRT allows the smoker to gradually wean themselves off the nicotine at a later date and improves a person's chances of quitting successfully compared with using willpower alone. There are different types of NRT and the right one will depend on a number of factors, such as how many cigarettes a person smokes and how often. Sometimes combining two forms of NRT may provide greater flexibility, particularly for those who experience breakthrough cravings. Electronic cigarettes are not currently regulated or licensed and therefore should not be recommended as a form of NRT.

€¢ Nicotine chewing gum

Available in two strengths €“ 2mg and 4mg €“ and in a choice of flavours, e.g. original, fruit and mint. Brands available include Nicorette, Nicotinell and NiQuitin. Nicotine gum should be chewed slowly until the taste becomes strong, then 'parked' between the cheek and the gum to allow the nicotine to be absorbed through the lining of the mouth. When the taste fades, the gum should be chewed again. Heartburn, flatulence, hiccups, salivation, nausea and vomiting may occur, but are transient. Denture wearers may find nicotine gum unsuitable. Nicotine gum is best suited to smokers with an irregular smoking pattern. The 2mg strength is aimed at those who smoke less than 20 cigarettes a day and the 4mg strength for those who smoke more than 20 a day.

€¢ Nicotine patch

Two types are available €“ a 24-hour patch to be worn day and night (e.g. Nicotinell, NiQuitin Clear), and a 16-hour patch applied first thing in the morning and removed at bedtime (e.g. Nicorette Invisipatch) Nicorette Invispatches are available in three strengths: 25mg, 15mg and 10mg, as are Nicotinell Patches: 21mg (Step 1), 14mg (Step 2) and 7mg (Step 3) options. The same strengths are also available in the NiQuitin Clear range. A patch should be applied to a clean, dry, hairless area of skin either on the upper arm or thigh. The site should be changed daily. Patches should not be applied if the skin is red, broken or irritated. Occasionally, itching, burning and redness may occur at the site of application. Nicotine patches are most suitable for smokers who have a regular smoking pattern and don't miss the hand-to-mouth action of smoking.

€¢ Nicotine inhalation device

The Nicorette Inhalator is best suited to smokers who miss the physical hand-to-mouth action of smoking. An inhalator consists of a mouthpiece containing a plug impregnated with 10mg nicotine that is absorbed via oral inhalation. It has a mild menthol flavour. The nicotine vapour is inhaled either by shallow puffing or deep inhaling and the nicotine is absorbed through the mouth, not the lungs. Local adverse effects are relatively common and include coughing, hiccups, sinusitis, mouth irritation and a sore throat.

€¢ Nicotine sublingual tablets and lozenges

Brands include Nicorette Microtab 2mg sublingual tablet, Nicorette Cools Lozenges (2mg and 4mg), Nicotinell Mint Lozenge (1mg and 2mg) and NiQuitin Lozenges (4mg /Step 1 and 2mg /Step 2). Sublingual tablets and lozenges release nicotine, which is absorbed across the mucosa in the mouth. The tablet should be kept under the tongue, where it slowly disintegrates. The lozenge is sucked until the taste becomes strong, then lodged between the gum and cheek. When the taste fades, the lozenge should be sucked again. These forms of NRT are best suited to smokers with an irregular smoking pattern who want a discreet and flexible form of NRT. The lozenge may lead to increased salivation and the tablet may leave a peppery taste in the mouth. Any nausea, GI discomfort, hiccups and coughing should be transient.

€¢ Nicotine nasal spray

Nicorette Nasal Spray releases a nicotine solution of 10mg/ml that is rapidly absorbed into the bloodstream. It is best suited for highly dependent or heavy smokers, and those who experience strong cravings. To use, the spray bottle should be directed at an angle into the nostril. Local irritation occurs most commonly during the first 48 hours of use and can include nasal irritation, a sore throat and a runny nose.

€¢ Nicotine mouthspray

Nicorette QuickMist Mouthspray is a fast acting, fine spray that's said to start working in 60 seconds. The small dispenser is easy to transport and can be used as cravings start. To use, angle the spray nozzle towards the open mouth, holding it as close as possible. Release one spray into the mouth, avoiding the lips. For best results the user should avoid swallowing straight after spraying. If cravings do not subside after one spray, a second spray can be administered. The maximum dose is two sprays at a time, four sprays in an hour and 64 sprays per day. Common side effects include a mild, burning sensation on the lips and mild hiccups.

€¢ Nicotine oral strips

NiQuitin Strips dissolve on the tongue and are said to offer craving relief in just 50 seconds by releasing nicotine in the mouth. The strip should fully dissolve in three minutes.

NRT can increase a person's chances of succesfully stopping smoking