If your symptoms do not improve within a few days, or if they become worse, check with your doctor.
This medicine may cause serious allergic reactions including anaphylaxis, which can be life-threatening and require immediate medical attention. Call your doctor right away if you have a rash; itching; hives; hoarseness; shortness of breath; trouble with breathing; trouble with swallowing; or any swelling of your hands, face, or mouth after you receive this medicine.
Serious skin reactions can occur with this medicine. Check with your doctor right away if you have blistering, peeling, or loosening of the skin; red skin lesions; severe acne or skin rash; sores or ulcers on the skin; or fever or chills while you are using this medicine.
Liver problems can occur while using this medicine. Stop using this medicine and check with your doctor right away if you have dark urine, clay-colored stools, abdominal or stomach pain, or yellow eyes or skin.
Norfloxacin may cause some people to become dizzy, lightheaded, drowsy, or less alert than they are normally. Make sure you know how you react to this medicine before you drive, use machines, or do anything else that could be dangerous if you are dizzy or are not alert. If these reactions are especially bothersome, check with your doctor.
Norfloxacin may cause diarrhea, and in some cases it can be severe. It may occur 2 months or more after you stop using this medicine. Do not take any medicine to treat diarrhea without first checking with your doctor. Diarrhea medicines may make the diarrhea worse or make it last longer. If you have any questions about this or if mild diarrhea continues or gets worse, check with your doctor.
Tell your doctor right away if you start having numbness, tingling, or burning pain in your hands, arms, legs, or feet. These may be symptoms of a condition called peripheral neuropathy.
Norfloxacin may rarely cause inflammation or even tearing of a tendon (the cord that attaches muscles to bones). The risk of having tendon problems may be increased if you are over 60 years of age, using steroid medicines (e.g., dexamethasone, prednisolone, prednisone, or Medrol®), if you have severe kidney problems, a history of tendon problems (e.g., rheumatoid arthritis), or if you have received an organ (e.g., heart, kidney, or lung) transplant. If you get sudden pain or swelling in a tendon after exercise (e.g., in the ankle, back of the knee or leg, shoulder, elbow, or wrist), stop using this medicine and check with your doctor right away. Refrain from exercise until your doctor says otherwise.
Some people who take norfloxacin may become more sensitive to sunlight than they are normally. Exposure to sunlight, even for brief periods of time, may cause severe sunburn, or skin rash, redness, itching, or discoloration. When you begin using this medicine:
- Stay out of direct sunlight, especially between the hours of 10:00 a.m. and 3:00 p.m., if possible.
- Wear protective clothing, including a hat and sunglasses.
- Apply a sun block product that has a skin protection factor (SPF) of at least 15. Some people may require a product with a higher SPF number, especially if they have a fair complexion. If you have any questions about this, check with your doctor.
- Do not use a sunlamp or tanning bed or booth.
If you have a severe reaction from the sun, check with your doctor.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.