There can be side effects from taking nicotine replacement products, as Nicotinell explains below.
General side effects of nicotine replacement products include vivid dreams, due to a low, therapeutic dose of nicotine being the active ingredient in nicotine replacement products, headaches, nausea and other digestive problems.
Some users may experience skin irritation with use of the nicotine patch, with a rash possibly developing at the location where the patch is applied. Take note that they could be a result of a reaction to the sticky backing on the patch, or due to the nicotine found in it. It is recommended that those with allergies to adhesive or sensitive skin refrain from using patches as a means of nicotine replacement therapy.
Opt for nicotine lozenges and side effects to look out for are hiccups, heartburn, excessive gas or an upset stomach — the latter is particularly common if you swallow the lozenge.
There are distinct side effects which could be seen from using nicotine gum too, including a tingling feeling on the tongue while the gum is being chewed, as well as jaw pain as a result of chewing. With the latter in mind, it is recommended that you do not choose gum if you have problems with the jaw joint — this could include temporomandibular.
Be sure to carefully read the user guide inside your package for a complete list of possible side effects.