It is very important that your doctor check the progress of you or your child at regular visits to make sure that this medicine is working properly. Blood and urine tests may be needed to check for unwanted effects.
Using this medicine while you are pregnant can harm your unborn baby. Use an effective form of birth control to keep from getting pregnant. If you think you have become pregnant while using the medicine, tell your doctor right away.
Very rarely, this medicine has caused severe side effects. If you or your child start to have a skin rash, or if you think you are having a severe skin reaction, stop taking this medicine and call your doctor right away. Symptoms of a severe reaction may include a skin rash, skin color that is very pale or yellow, or skin with purple spots, along with a sore throat, fever, muscle pain, cough, and trouble with breathing.
This medicine, especially if you are receiving high doses or for a long period of time, may lower the number of platelets in your body, which are necessary for proper blood clotting. Because of this, you may bleed or get infections more easily. Talk with your doctor if you have concerns about this.
This medicine may cause diarrhea, and in some cases it can be severe. It may occur 2 months or more after you stop taking this medicine. Do not take any medicine to treat diarrhea without first checking with your doctor. If you have any questions or if mild diarrhea continues or gets worse, check with your doctor.
Check with your doctor right away if you or your child have abdominal or stomach cramps, bloating, watery and severe diarrhea, which may also be bloody, nausea or vomiting, or unusual tiredness or weakness. These may be symptoms of a serious intestinal infection.
This medicine may cause serious allergic reactions, including anaphylaxis. Anaphylaxis can be life-threatening and requires immediate medical attention. Check with your doctor right away if you or your child have a rash, itching, swelling of the face, tongue, and throat, trouble breathing, shortness of breath, or chest pain after you use the medicine.
This medicine may cause electrolyte problems, such as high potassium in the blood (hyperkalemia) and low sodium in the blood (hyponatremia). Tell your doctor right away if you have any of the following symptoms while using this medicine: confusion, weakness, muscle twitching, an irregular heartbeat, numbness or tingling in the hands, feet, or lips, or trouble breathing.
Before you have any medical tests, tell the medical doctor in charge that you or your child are taking this medicine. The results of some tests may be affected by this medicine.
Patients receiving anticonvulsant therapy (medicines to prevent seizures) may be at risk for a folate (vitamin B9) deficiency, which may increase the risk for side effects. Talk with your doctor if you have concerns about this.
Do not use this medicine for Pneumocystis jiroveci pneumonia (PCP) if you are also using leucovorin. Using these medicines together may cause these medicines to not work as well for you.
Do not take other medicines unless they have been discussed with your doctor. This includes leucovorin, other prescription or nonprescription (over-the-counter [OTC]) medicines and herbal or vitamin supplements.