Calcium and magnesium are naturally occurring minerals. Calcium is needed for bone formation and maintenance. Magnesium helps maintain muscle function and normal heart rhythm.

Mag64 is a combination medicine used as a supplement. Mag64 is given when your diet does not provide enough of these minerals, or when they are lost through perspiration.

Mag64 may also be used for purposes not listed in this medication guide.

Follow all directions on your medicine label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.

Use exactly as directed on the label, or as prescribed by your doctor.

Swallow the tablet whole and do not crush, chew, or break it.

Store at room temperature away from moisture and heat.

You should not use Mag64 if you have ever had an allergic reaction to an antacid or vitamin/mineral supplement that contains calcium carbonate or magnesium chloride.

Ask a doctor or pharmacist if this medicine is safe to use if you have:

• kidney disease;

• a history of kidney stones;

• heart disease; or

• a blockage in your intestines.

Ask a doctor before using this medicine if you are pregnant or breastfeeding. Your dose needs may be different during pregnancy or while you are nursing.

Since Mag64 is used when needed, you may not be on a dosing schedule. Skip any missed dose if it's almost time for your next dose. Do not use two doses at one time.

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.

Avoid taking other medicines at the same time you take Mag64.

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

Mag64 may cause serious side effects. Stop using Mag64 and call your doctor at once if you have:

• nausea, vomiting, stomach pain, loss of appetite, increased thirst or urination;

• muscle pain or weakness, joint pain;

• confusion, feeling tired or restless; or

• slow heart rate, drowsiness, feeling light-headed.

Common side effects of Mag64 may include:

• diarrhea;

• constipation; or

• upset stomach.

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.

Calcium carbonate can make it harder for your body to absorb certain drugs, making them less effective. If you take other medicines, take your Mag64 dose 2 hours before or 2 hours after you take the other medicine.

Tell your doctor about all your other medicines, especially:

• an antibiotic;

• heart or blood pressure medicine; or

• medicine to treat osteoporosis or Paget's disease of bone--Actonel, Boniva, Fosamax, Reclast, Zometa, and others.

This list is not complete. Other drugs may affect Mag64, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible drug interactions are listed here.