Nausea, vomiting, loss of appetite, or headache may occur. Take this medication with food to help minimize nausea. If any of these effects last or get worse, notify your doctor or pharmacist promptly.

This medication may cause your urine to turn dark yellow or brown in color. This effect is harmless and will disappear when the medication is stopped.

Remember that this medication has been prescribed because your doctor 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 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: cough that doesn't go away, chest pain, shortness of breath/trouble breathing, joint/muscle pain, bluish/purplish skin.

Tell your doctor right away if you have any serious side effects, including: headache that is severe or doesn't go away, new signs of infection (such as sore throat that doesn't go away, fever), easy bruising/bleeding, mental/mood changes, vision changes.

This drug may rarely cause serious (possibly fatal) liver disease, blood or nerve problems. Tell your doctor right away if you notice any of the following serious side effects: nausea/vomiting that doesn't stop, unusual tiredness, dark urine, yellowing of eyes/skin, fast/pounding heartbeat, numbness/tingling of the arms/legs, muscle weakness.

This medication may rarely cause a severe intestinal condition due to a bacteria called C. difficile. This condition may occur during treatment or weeks to months after treatment has stopped. Tell your doctor right away if you develop: diarrhea that doesn't stop, abdominal or stomach pain/cramping, blood/mucus in your stool.

If you have these symptoms, do not use anti-diarrhea or opioid products because they may make symptoms worse.

Use of this medication for prolonged or repeated periods may result in oral thrush or a new vaginal yeast infection (such as oral or vaginal fungal 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.