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Acetylcysteine (By mouth)

Acetylcysteine (a-seet-il-SIS-teen)

Helps prevent liver damage caused by an overdose of acetaminophen.

Brand Name(s):


There may be other brand names for this medicine.

When This Medicine Should Not Be Used:

This medicine is given to anyone who has taken an overdose of acetaminophen.

How to Use This Medicine:

Liquid, Powder, Fizzy Tablet

  • Your doctor will tell you how much medicine to use. Do not use more than directed. This medicine works best when given as soon as possible after the overdose. You will receive the first few doses while you are in the hospital, and then you may need to keep taking it for several days after you go home. Do not stop taking this medicine until your doctor says it is okay.
  • Oral solution: Mix the oral solution with a diet soft drink and drink the mixture immediately.
  • Effervescent tablets: Dissolve the effervescent tablets in water and drink the mixture within 2 hours.
  • If you vomit within 1 hour after you take your medicine, take another dose to make up for it.
  • Read and follow the patient instructions that come with this medicine. Talk to your doctor or pharmacist if you have any questions.

Drugs and Foods to Avoid:

Ask your doctor or pharmacist before using any other medicine, including over-the-counter medicines, vitamins, and herbal products.

Warnings While Using This Medicine:

  • Tell your doctor if you are pregnant or breastfeeding, or if you have kidney disease, liver disease, bleeding in the esophagus, heart failure, stomach ulcers, or had an allergic reaction to any medicine. Tell your doctor if you are on a low sodium diet or if you have a history of alcohol addiction.
  • This medicine may increase the risk of bleeding in your esophagus and stomach.
  • Your doctor will do lab tests at regular visits to check on the effects of this medicine. Keep all appointments.

Possible Side Effects While Using This Medicine:

Call your doctor right away if you notice any of these side effects:

  • Allergic reaction: Itching or hives, swelling in your face or hands, swelling or tingling in your mouth or throat, chest tightness, trouble breathing
  • Rash with or without a fever
  • Severe or ongoing vomiting

If you notice these less serious side effects, talk with your doctor:

  • Mild nausea, vomiting, or upset stomach

If you notice other side effects that you think are caused by this medicine, tell your doctor

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088

Last Updated: 5/1/2020

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