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When Shouldn’t I Take Alli?

Always tell your doctor about all the medications you’re taking. Alli can interact with certain drugs, affecting their levels or how they work in your body, which could lead to life-threatening consequences. Check with your doctor if you’re taking warfarin (a blood thinner), diabetes or thyroid medications, or other weight loss drugs. In some cases, your dosages may need to be adjusted.

Don’t take Alli if:


Side Effects of Alli

Loose stools and other bowel movement changes are the most common side effects of Alli. Symptoms typically occur during the first few weeks of treatment and then go away. However, they may continue.

Tell your doctor if you have any of the following symptoms and they become severe or do not go away:

  • Difficulty controlling bowel movements
  • Loose, frequent stools
  • Oily or fatty stools
  • Oily spots on undergarments
  • Stomach or rectum pain
  • Passing gas more often
  • Urgent need to have a bowel movement
  • Anxiety
  • Changes in your menstrual cycle
  • Headaches

Emergency Side Effects of Alli

Call 911 or your doctor immediately if you develop any of these symptoms:


Alli has been linked to severe liver injury in rare cases, though it has mostly occurred in those taking the prescription-strength dose (Xenical). Stop taking Alli and call your doctor immediately if you develop any of these possible signs of liver damage:

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