Before taking norfloxacin, tell your doctor or pharmacist if you are allergic to it; or to other quinolone antibiotics such as ciprofloxacin, gemifloxacin, levofloxacin; 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.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: joint/tendon problems (such as tendonitis, bursitis), kidney disease, mental/mood disorders (such as depression), a certain muscle condition (myasthenia gravis), nerve problems (such as peripheral neuropathy), seizure disorder, blood vessel problems (such as aneurysm or blockage of the aorta or other blood vessels, hardening of the arteries), high blood pressure, certain genetic conditions (Marfan syndrome, Ehlers-Danlos syndrome).

Norfloxacin 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 norfloxacin, 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 norfloxacin safely.

This medication may rarely cause serious changes in blood sugar, especially if you have diabetes. Check your blood sugar regularly as directed and share the results with your doctor. Watch for symptoms of high blood sugar, such as increased thirst/urination. Also watch for symptoms of low blood sugar such as sudden sweating, shaking, fast heartbeat, hunger, blurred vision, dizziness, or tingling hands/feet. It is a good habit to carry glucose tablets or gel to treat low blood sugar. If you don't have these reliable forms of glucose, rapidly raise your blood sugar by eating a quick source of sugar such as table sugar, honey, or candy, or by drinking fruit juice or non-diet soda. Tell your doctor right away about the reaction and the use of this product. To help prevent low blood sugar, eat meals on a regular schedule, and do not skip meals. Your doctor may need to switch you to another antibiotic or adjust your diabetes medications if any reaction occurs.

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

This medication may make you more sensitive to the sun. Limit your time in the sun. Avoid tanning booths and sunlamps. Use sunscreen and wear protective clothing when outdoors. Tell your doctor right away if you get sunburned or have skin blisters/redness.

Norfloxacin may cause live bacterial vaccines (such as typhoid vaccine) to not work well. Tell your health care professional that you are using norfloxacin before having any immunizations/vaccinations.

Before having surgery, tell your doctor or dentist about all the products you use (including prescription drugs, nonprescription drugs, and herbal products).

Children may be at greater risk for joint/tendon problems while using this drug. Discuss the risks and benefits with the doctor.

Older adults may be at greater risk for tendon problems (especially if they are also taking corticosteroids such as prednisone or hydrocortisone), QT prolongation, and a sudden tear/break in the main blood vessel (aorta).

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

It is unknown if this drug passes into breast milk. However, similar drugs pass into breast milk. Consult your doctor before breastfeeding.