Take this medication by mouth with food as directed by your doctor, usually twice daily (every 12 hours). Swallow the medication whole for best results. Do not use magnesium trisilicate-containing antacids while taking this medication. These antacids can bind with nitrofurantoin, preventing its full absorption into your system. For the best effect, take this antibiotic at evenly spaced times. To help you remember, take this medication at the same time(s) every day. Continue to take this medication until the full prescribed amount is finished, even if symptoms disappear after a few days. Stopping the medication too early may allow bacteria to continue to grow, which may result in a return of the infection. Inform your doctor if your condition persists or worsens.

Nausea, headache may occur. If any of these effects persist or worsen, notify your doctor or pharmacist promptly. Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects. This medication may cause your urine to turn dark yellow or brown in color. This is usually a harmless, temporary effect and will disappear when the medication is stopped. However, dark brown urine can also be a sign of rare side effects (liver problems or anemia). Therefore, seek immediate medical attention if you notice dark urine along with any of the following symptoms: persistent nausea/vomiting, stomach/abdominal pain, yellowing eyes/skin, tiredness, fast/pounding heartbeat. Tell your doctor right away if any of these rare but very serious side effects occur: eye pain, vision changes, mental/mood changes, persistent/severe headaches, new signs of infection (e.g., fever, persistent sore throat), easy bruising/bleeding. Seek immediate medical attention if you develop the following rare but very serious side effects: numbness/tingling of the hands/feet, unusual muscle weakness. This medication may rarely cause very serious (possibly fatal) lung problems. Lung problems may occur within the first month of treatment or after long-term use of nitrofurantoin (generally for 6 months or longer). Get medical help right away if you develop symptoms of lung problems, including: persistent cough, chest pain, shortness of breath/trouble breathing, joint/muscle pain, bluish/purplish skin. This medication may rarely cause a severe intestinal condition (Clostridium difficile-associated diarrhea) due to a resistant bacteria. This condition may occur during treatment or even weeks to months after treatment has stopped. Do not use anti-diarrhea or opioid medications if you have the following symptoms because these products may make them worse. Tell your doctor right away if you develop: persistent diarrhea, abdominal or stomach pain/cramping, blood/mucus in your stool. Use of nitrofurantoin for prolonged or repeated periods may result in oral thrush or a new vaginal yeast infection. Contact your doctor if you notice white patches in your mouth, a change in vaginal discharge, or other new symptoms. A very serious allergic reaction to this drug is rare. However, get medical help right away if you notice any symptoms of a serious allergic reaction, including: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing. This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist. In the US - Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088 or at www.fda.gov/medwatch. In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Store at room temperature between 59-86 degrees F (15-30 degrees C) away from light and moisture. Do not store in the bathroom. Keep all medicines away from children and pets. Do not flush medications down the toilet or pour them into a drain unless instructed to do so. Properly discard this product when it is expired or no longer needed. Consult your pharmacist or local waste disposal company for more details about how to safely discard your product.

(See also How to Use section). Your healthcare professionals (e.g., doctor or pharmacist) may already be aware of any possible drug interactions and may be monitoring you for it. Do not start, stop, or change the dosage of any medicine before checking with them first. Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially: certain drugs to treat gout (uricosuric drugs such as sulfinpyrazone). Although most antibiotics are unlikely to affect hormonal birth control such as pills, patch, or ring, a few antibiotics (such as rifampin, rifabutin) can decrease their effectiveness. This could result in pregnancy. If you use hormonal birth control, ask your doctor or pharmacist for more details. This medication may interfere with certain laboratory tests (certain urine glucose tests), possibly causing false test results. Make sure laboratory personnel and all your doctors know you use this drug. This document does not contain all possible interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you, and share the list with your doctor and pharmacist.

If someone has overdosed and has serious symptoms such as passing out or trouble breathing, call 911. Otherwise, call a poison control center right away. US residents can call their local poison control center at 1-800-222-1222. Canada residents can call a provincial poison control center.