Therapeutic nicotine, or NRT, works by replacing some of the nicotine that smokers get from cigarettes, but without the tar and poisonous chemicals. NRT provides receptors in the brain with enough nicotine to overcome the cravings associated with quitting smoking. Using NRT allows smokers to gradually wean themselves off nicotine and improves their chances of quitting successfully compared with willpower alone.

There are several different types of NRT and the right one depends on a number of different factors, including how dependent the person is on their habit. Combining two forms of NRT can sometimes 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 or 4mg €“ and in a selection of flavours (e.g. original, fruit and mint). Brands 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, increased salivation, nausea and vomiting may transiently occur. Nicotine gum is best suited to smokers with an irregular smoking pattern. The 2mg strength is for those who smoke less then 20 cigarettes a day and the 4mg strength is for those who smoke more than 20 a day. Denture wearers may find gum unsuitable.

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 to be applied first thing in the morning and removed before bed (e.g. Nicorette Invisi Patch).

Nicorette Invisi Patch is available in three strengths: 10mg, 15mg and 25mg, as are Nicotinell Patches: 21mg (Step 1), 14mg (Step 2) and 7mg (Step 3). The same strengths are also available in the Niquitin Clear range. Patches should be applied to a clean, dry, hairless area of skin either on the upper arm or thigh.

The application site should be changed daily. Patches should not be applied if the skin is red, cut or irritated. Itching, burning and redness occasionally occur at the site of application. Nicotine patches are best suited to smokers with a regular smoking pattern who do not 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. It consists of a mouthpiece containing a plug impregnated with 15mg nicotine that is absorbed via oral inhalation. The nicotine vapour is inhaled either by shallow puffing or deep inhaling.

The nicotine is absorbed through the mouth, not the lungs. Local adverse effects are relatively common and include coughing, hiccups, sinusitis, sore throat and mouth irritation.

Nicotine sublingual tablets and lozenges

Brands include Nicorette Microtab 2mg sublingual tablet, Nicorette Cools lozenges (2mg and 4mg), Nicotinell lozenges (2mg and 4mg) 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 lodged under the tongue where it slowly disintegrates.

The lozenge should be sucked until the taste becomes strong, then lodged between the gum and cheek. Once 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. Lozenges may lead to increased salivation and tablets may leave a peppery taste in the mouth. Any nausea, GI discomfort, hiccups or coughing should be transient.

Nicotine nasal spray

Nicorette Nasal Spray releases a nicotine 10mg/ml solution that is rapidly absorbed into the bloodstream. It is best suited to highly dependent or heavy smokers, and those who experience strong cravings.

The spray bottle should be positioned at an angle into the nostril. Local irritation such as nasal irritation, a sore throat or a runny nose most commonly occur during the first 48 hours of use.

Nicotine mouthspray

Nicorette Quickmist Mouthspray is a fine spray that is said to start working in just 60 seconds. The small dispenser is convenient to transport and can be administered at the onset of cravings. To use, the spray nozzle should be pointed towards the open mouth, holding it as close as possible.

One spray should be released into the mouth, avoiding the lips. For best results, users should avoid swallowing immediately after application. 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 an hour and 64 sprays a 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 relief from cravings in just 50 seconds. They work by releasing nicotine in the mouth. The strip will dissolve fully in approximately three minutes.