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Medications and Drugs

Brand Names: MST, Nuprin Backache Caplet

Generic Name: magnesium salicylate (Pronunciation: mag NEE zee um sa LIS i late)

What is magnesium salicylate (MST, Nuprin Backache Caplet)?

Magnesium salicylate is a non-steroidal anti-inflammatory drug (NSAID) in a group of drugs called salicylates (sa-LIS-il-ates). This medicine works by reducing substances in the body that cause pain, fever, and inflammation.

Magnesium salicylate is used to reduce pain, swelling, and joint stiffness caused by arthritis.

Magnesium salicylate may also be used for purposes not listed in this medication guide.

What are the possible side effects of magnesium salicylate (MST, Nuprin Backache Caplet)?

Get emergency medical help if you have any of these signs of an allergic reaction: hives; difficult breathing; swelling of your face, lips, tongue, or throat.

Stop using this medication and call your doctor at once if you have a serious side effect such as:

  • chest pain, severe dizziness, shortness of breath, slurred speech, problems with vision or balance;
  • sudden numbness or weakness, especially on one side of the body;
  • feeling like you might pass out;
  • black, bloody, or tarry stools;
  • coughing up blood or vomit that looks like coffee grounds;
  • blood in your urine, urinating more or less than usual;
  • hearing problems, ringing in your ears;
  • swelling, rapid weight gain;
  • easy bruising or bleeding, unusual weakness, fever, chills, sore throat, flu symptoms;
  • fast or pounding heartbeats;
  • severe stomach pain, ongoing nausea or vomiting; or
  • dark urine, jaundice (yellowing of the skin or eyes).

Less serious side effects may include:

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

What is the most important information I should know about magnesium salicylate (MST, Nuprin Backache Caplet)?

You should not use this medication if you are allergic to aspirin or to an NSAID (non-steroidal anti-inflammatory drug), or if you have recently used cidofovir (Vistide) or ketorolac (Toradol).

Before taking magnesium salicylate, tell your doctor if you have asthma, heart disease, high blood pressure, stomach or intestinal bleeding, diabetes, anemia, a bleeding disorder, liver or kidney disease, nasal polyps, a genetic enzyme deficiency, or if you are dehydrated.

This medicine may cause life-threatening heart or circulation problems such as heart attack or stroke, especially if you use it long term. Do not use magnesium salicylate just before or after heart bypass surgery (coronary artery bypass graft, or CABG).

Get emergency medical help if you have chest pain, weakness, shortness of breath, slurred speech, or problems with vision or balance.

This medicine may also cause serious effects on the stomach or intestines, including bleeding or perforation (forming of a hole). These conditions can be fatal and can occur without warning while you are taking magnesium salicylate, especially in older adults.

Call your doctor at once if you have symptoms of stomach bleeding such as black, bloody, or tarry stools, or coughing up blood or vomit that looks like coffee grounds.

This medication should not be given to a child or teenager who has a fever, especially if the child also has flu symptoms or chicken pox. Salicylates can cause a serious and sometimes fatal condition called Reye's syndrome in children.

Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

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