Some patients - for example those with kidney disease - can be at risk of side effects if they ingest these substances.
The new rule requires manufacturers to include the amount of the substance per dosage unit (e.g. per tablet) if they contain: 5 mg or more of sodium in a single dose; 20 mg or more of calcium in a single dose; 8 mg or more of magnesium in a single dose; and 5 mg or more of potassium in a single dose.
They also require new warnings on the label to alert people with kidney stones, decreased kidney function due to kidney disease, or people who are on sodium, calcium, magnesium, or potassium-restricted diets to consult their doctors before using products for oral ingestion that contain: more than 140 mg of sodium as the maximum daily dose; more than 3.2 grams of calcium as the maximum daily dose; more than 600 mg of magnesium as the maximum daily dose; or more than 975 mg potassium as the maximum daily dose.
In addition, the agency is proposing to extend sodium content labelling requirements to OTC rectal drug products containing sodium phosphates.
FDA is taking this action because people with certain medical conditions may be at risk for serious or life-threatening electrolyte imbalances when using these products.
"These new warnings provide an extra level of safety for people who may be especially sensitive to these commonly used OTC ingredients," said acting FDA Commissioner Lester Crawford.
Sodium may be related to high blood pressure and is a concern for individuals with congestive heart failure.
In people with kidney disease, blood levels of calcium, magnesium, and potassium can reach potentially dangerous levels due to their decreased elimination.
People with kidney stones need to carefully monitor their calcium intake.
The final rules become effective on 23 April and full compliance with them is required by 25 September 2005.