Acetaminophen/muscle relaxer (By mouth)


Treats pain, decreases fever, and helps decrease certain allergy and hay fever symptoms.

Brand Name(s)

Asp 300/200/20, Dologesic, Dolorex, Novagesic, Percogesic, Rhinoflex-650, Staflex

When This Medicine Should Not Be Used

How to Use This Medicine

Tablet, Capsule, Liquid Filled Capsule, Liquid

  • Your doctor will tell you how much medicine to use. Do not use more than directed.
  • This medicine contains acetaminophen. Read the labels of all other medicines you are using to see if they also contain acetaminophen, or ask your doctor or pharmacist. Do not use more than 4 grams (4,000 milligrams) total of acetaminophen in one day.
  • Do not use this medicine for pain for more than 10 days in an adult, or for more than 5 days in a child. Do not take it for fever for more than 3 days, unless your doctor tells you to.
  • Liquid: Measure the oral liquid medicine with a marked measuring spoon, oral syringe, or medicine cup.
  • Missed dose: Take a dose as soon as you remember. If it is almost time for your next dose, wait until then and take a regular dose. Do not take extra medicine to make up for a missed dose.
  • Store the medicine in a closed container at room temperature, away from heat, moisture, and direct light.

Drugs and Foods to Avoid

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

  • Some medicines and foods can affect how this medicine works. Tell your doctor if you are taking any medicine that contains acetaminophen.
  • Do not drink alcohol while you are using this medicine. Acetaminophen can damage your liver, and alcohol can increase this risk. If you regularly drink 3 or more alcoholic drinks every day, do not take any medicines that contain acetaminophen without asking your doctor. A drink of alcohol is 12 ounces of beer, 4 ounces of wine, or 1 ounce of liquor.
  • Tell your doctor if you use anything else that makes you sleepy. Some examples are allergy medicine, narcotic pain medicine, and alcohol.

Warnings While Using This Medicine

  • Tell your doctor if you are pregnant or breastfeeding.
  • Tell your doctor if you have glaucoma, kidney or liver problems, breathing problems such as asthma or COPD (emphysema or chronic bronchitis), or trouble urinating due to an enlarged prostate gland. Tell your doctor if you drink alcohol on a regular basis.
  • This medicine may make you drowsy. Do not drive or use machines if you are not alert.
  • Tell any doctor or dentist who treats you that you are using this medicine. This medicine may affect certain medical test results.
  • Keep all medicine out of the reach of children. Never share your medicine with anyone.

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
  • Fever that continues for longer than 3 days after you started taking this medicine
  • Pain that continues for longer than 10 days after you started taking this medicine
  • Skin rash, redness, or swelling
  • Unusual bleeding, bruising, or weakness

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

  • Excitability or other mood or behavior changes, especially in children
  • Nausea or vomiting
  • New or worsening symptoms

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

Version Info

  • Last reviewed on 12/4/2015

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