What are some possible adverse side effects of the nicotine patch?

The most COMMON side effects when using a Nicotine Patch are:

Abnormal dreams; headache; mild dizziness; mild redness, itching, or burning at the application site; nervousness; sweating; trouble sleeping; vivid dreams.

Some less common but severe side effects are:

Severe allergic reactions (rash; hives; itching; difficulty breathing; tightness in the chest; swelling of the mouth, face, lips, or tongue); blurred vision; fast or irregular heartbeat; nausea; severe or persistent dizziness or headache; stomach pain or vomiting; swelling or persistent (more than 4 days) redness at the application site

Of course another potential side effect could be nicotine poisoning if too many patches are used at one time. Symptoms of nicotine poisoning include:

• Vomiting and nausea, diarrhea
• Headaches
• Difficulty breathing
• Pallor
• Sweating
• Palpitations
• Lisps
• Stomach pains/cramps
• Seizures
• Weakness
• Drooling