Before taking loperamide, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

If you have any of the following health problems, consult your doctor or pharmacist before using this medication: stomach/abdominal pain without diarrhea, bowel obstruction (such as ileus, megacolon, abdominal distention), black/tarry stool, blood/mucus in your stool, high fever, HIV infection/AIDS, liver problems, certain stomach/intestinal infections (such as Salmonella, Shigella), certain type of bowel disease (acute ulcerative colitis).

The rapidly dissolving tablets may contain aspartame or phenylalanine. If you have phenylketonuria (PKU) or any other condition that requires you to restrict your intake of aspartame or phenylalanine, consult your doctor or pharmacist regarding the safe use of this medicine.

Antibiotics may rarely cause a severe intestinal condition due to a bacteria called C. difficile. Symptoms include: diarrhea that doesn't stop, abdominal or stomach pain/cramping, or blood/mucus in your stool. This condition may occur during treatment or weeks to months after treatment has stopped. This medication may make this condition worse. Do not use this anti-diarrhea product, especially after recent antibiotic use, if you have the above symptoms without talking with your doctor first.

Loperamide may cause a condition that affects the heart rhythm (QT prolongation). QT prolongation can rarely cause serious (rarely fatal) fast/irregular heartbeat and other symptoms (such as severe dizziness, fainting) that need medical attention right away.

The risk of QT prolongation may be increased if you have certain medical conditions or are taking other drugs that may cause QT prolongation. Before using loperamide, tell your doctor or pharmacist of all the drugs you take and if you have any of the following conditions: certain heart problems (heart failure, slow heartbeat, QT prolongation in the EKG), family history of certain heart problems (QT prolongation in the EKG, sudden cardiac death).

Low levels of potassium or magnesium in the blood may also increase your risk of QT prolongation. This risk may increase if you use certain drugs (such as diuretics/"water pills") or if you have conditions such as severe sweating, diarrhea, or vomiting. Talk to your doctor about using loperamide safely.

This drug may make you dizzy or drowsy. Alcohol or marijuana (cannabis) can make you more dizzy or drowsy. Do not drive, use machinery, or do anything that needs alertness until you can do it safely. Avoid alcoholic beverages. Talk to your doctor if you are using marijuana (cannabis).

Older adults may be more sensitive to the side effects of this drug, especially QT prolongation (see above).

Children may be more sensitive to the side effects of this drug, especially drowsiness. Children are also at a higher risk for dehydration. See also Warning and How to Use sections.

During pregnancy, this medication should be used only if clearly needed. Discuss the risks and benefits with your doctor.

This drug passes into breast milk but is unlikely to harm a nursing infant. Consult your doctor before breastfeeding.