Along with its needed effects, nicotine replacement may cause some unwanted or undesirable effects. Generally, nicotine replacement is well tolerated and many people will not experience unwanted effects. The frequency and severity of these effects is dependant on many factors including dose, duration of therapy and individual susceptibility. Possible unwanted effects include:

• belching
• increased appetite
• injury or irritation to mouth, teeth or dental work (chewing gum only)
• trouble sleeping
• unusual dreams

Rare:

• fast or irregular heartbeat
• high blood pressure
• hives
• rash
• stomach pain
• coughing
• irritability

Nicotine replacement therapy provides a lower level of nicotine to your blood than cigarettes, and allows the body's need for nicotine to gradually go away. It works as a temporary aid to help with smoking cessation by reducing nicotine cravings and nicotine withdrawal symptoms.

Do not continue to smoke while using nicotine replacement products.(If using nicotine gum to cut back, do not smoke at the same time as chewing gum.) If you smoke or use other nicotine-containing products while using nicotine replacement you may get a nicotine overdose. Signs of an overdose include headaches, dizziness, nausea, abdominal pain, drooling, vomiting, diarrhea, cold sweat, blurred vision, difficulty with hearing, mental confusion, weakness and fainting, rapid heartbeat and difficulty breathing. If you experience any of these symptoms contact your doctor or Poison Control Centre at once.

Do not use nicotine replacement therapy if you have:

• certain heart conditions (e.g. heart attacks, heart beat irregularities)is contraindicated.
• recent stroke
• skin diseases
• known allergy to the patches or to nicotine

Consult your doctor first if you have ever had any of the following:

• irregular heart beat (arrhythmia)
• high blood pressure
• overactive thyroid (hyperthyroidism)
• stomach ulcers
• kidney or liver disease
• diabetes requiring insulin
• treatment for poor circulation
• rashes from adhesive tape or bandages

Drug Interactions: It is important to tell your doctor and pharmacist of any prescription or over-the-counter medications you are taking. In some cases the dose of one or both drugs may need to be altered or another drug may be prescribed. The concentration of medication in the body may be altered by smoking cessation with or without nicotine replacement. The dosage of certain medications may require adjustment. Drugs whose concentrations may be affected by smoking cessation include:

• acetaminophen
• imipramine
• oxazepam
• propranolol
• theophylline
• insulin
• prazosin
• labetalol

Use in pregnancy: Consult your doctor or pharmacist if you suspect you are pregnant.
Use while breastfeeding: Consult your doctor or pharmacist before use.