Before Using This Medicine

In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For nitrofurantoin, the following should be considered:

Allergies—Tell your doctor if you have ever had any unusual or allergic reaction to nitrofurantoin or to any related medicines such as furazolidone (e.g., Furoxone) or nitrofurazone (e.g., Furacin). Also tell your health care professional if you are allergic to any other substances, such as foods, preservatives, or dyes.

Pregnancy—Nitrofurantoin should not be used if you are within a week or 2 of your delivery date or during labor and delivery. It may cause problems in the infant. Studies in animals have shown some problems when given in doses many times the human dose. Before taking this medicine, make sure your doctor knows if you are pregnant or if you may become pregnant.

Breast-feeding—Nitrofurantoin passes into the breast milk in small amounts and may cause problems in nursing babies, especially those with glucose-6-phosphate dehydrogenase (G6PD) deficiency. It may be necessary for you to take another medicine or to stop breast-feeding during treatment. Be sure you have discussed the risks and benefits of the medicine with your doctor.

Children—This medicine has been tested in children 1 month of age and older and, in effective doses, has not been shown to cause different side effects or problems in children than it does in adults. However, infants up to 1 month of age should not be given this medicine because they are especially sensitive to the effects of nitrofurantoin.

Older adults—Elderly people may be more sensitive to the effects of nitrofurantoin. This may increase the chance of side effects during treatment.

Other medicines—Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. When you are taking nitrofurantoin, it is especially important that your health care professional know if you are taking any of the following:

• Acetohydroxamic acid (e.g., Lithostat) or
• Antidiabetics, oral (diabetes medicine you take by mouth) or
• Dapsone or
• Furazolidone (e.g., Furoxone) or
• Methyldopa (e.g., Aldomet) or
• Primaquine or
• Procainamide (e.g., Pronestyl) or
• Quinidine (e.g., Quinidex) or
• Sulfonamides (sulfa medicine) or
• Sulfoxone (e.g., Diasone) or
• Vitamin K (e.g., AquaMEPHYTON, Synkayvite)—Patients who take nitrofurantoin with any of these medicines may have an increase in side effects affecting the blood

• Carbamazepine (e.g., Tegretol) or
• Chloroquine (e.g., Aralen) or
• Cisplatin (e.g., Platinol) or
• Cytarabine (e.g., Cytosar-U) or
• Diphtheria, tetanus, and pertussis (DTP) vaccine or
• Disulfiram (e.g., Antabuse) or
• Ethotoin (e.g., Peganone) or
• Hydroxychloroquine (e.g., Plaquenil) or
• Lindane, topical (e.g., Kwell) or
• Lithium (e.g., Lithane) or
• Mephenytoin (e.g., Mesantoin) or
• Mexiletine (e.g., Mexitil) or
• Other anti-infectives by mouth or by injection (medicine for infection) or
• Pemoline (e.g., Cylert) or
• Phenytoin (e.g., Dilantin) or
• Pyridoxine (e.g., Hexa-Betalin) (with long-term, high-dose use) or
• Vincristine (e.g., Oncovin)—Patients who take nitrofurantoin with any of these medicines, or who have received a DTP vaccine within the last 30 days or are going to receive a DTP vaccine may have an increase in side effects affecting the nervous system

• Probenecid (e.g., Benemid) or
• Sulfinpyrazone (e.g., Anturane)—Patients who take nitrofurantoin with either of these medicines may have an increase in side effects

• Quinine (e.g., Quinamm)—Patients who take nitrofurantoin with quinine may have an increase in side effects affecting the blood and the nervous system

Other medical problems—The presence of other medical problems may affect the use of nitrofurantoin. Make sure you tell your doctor if you have any other medical problems, especially:

• Anemia or
• Diabetes mellitus or
• Lung disease or
• Nerve damage or
• Other serious illness or
• Vitamin B deficiency—These conditions may increase the chance for side effects

• Glucose-6-phosphate dehydrogenase (G6PD) deficiency—Nitrofurantoin may cause anemia in patients with G6PD deficiency

• Kidney disease (other than infection)—The chance of side effects of this medicine may be increased and the medicine may be less effective in patients with kidney disease