Chantix Side Effects

Common and serious side effects of Chantix (varenicline), what to watch for, and when to call your doctor.

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Information reviewed July 24, 2026

Common side effects

This is not a complete list. Always consult a doctor or pharmacist.

  • Nausea
  • Vivid dreams
  • Insomnia
  • Headache
  • Mood changes

Serious warnings

Chantix has notable warnings and precautions. Tell your doctor about your medical history and any other medicines or supplements you take before starting Chantix.

When to call a doctor

As a general rule with any prescription medicine, contact your doctor about any side effect that is severe, persistent, or worries you. General guidance is to seek emergency care for signs of a serious allergic reaction to any medicine — such as trouble breathing or swelling of the face, lips, tongue, or throat.

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TVPills is an informational reference, not medical advice. Always talk to a licensed healthcare provider about your treatment.

Frequently asked questions

What are the most common side effects of Chantix?

Commonly reported side effects of Chantix (varenicline) include Nausea, Vivid dreams, Insomnia, Headache, and Mood changes. This is not a complete list — tell your doctor or pharmacist about any side effects you experience.

Does Chantix have any serious or boxed warnings?

Chantix has notable warnings and precautions. Tell your doctor about your medical history and any other medicines or supplements you take before starting Chantix.

When should I call my doctor about Chantix side effects?

As a general rule with any prescription medicine, call your doctor about any side effect that is severe, doesn't go away, or worries you. General guidance is to seek emergency care for signs of a serious allergic reaction to any medicine — such as trouble breathing or swelling of the face, lips, tongue, or throat. For advice about your situation, talk to a licensed healthcare provider.

Where can I find the full list of Chantix side effects?

The side effects above are commonly reported ones recorded for Chantix (varenicline); they are not a complete list. For the full prescribing information and medication guide, check the official Chantix label or ask your doctor or pharmacist.

Should I stop taking Chantix if I have side effects?

General medical guidance is not to stop a prescription medicine on your own without talking to your doctor first. Your doctor can advise whether to continue, adjust, or change your treatment. This page is informational and not medical advice.

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