Your child is receiving high dose IV methotrexate. Side effects of methotrexate include kidney damage and mouth sores. It is important to know what to watch for, and when and who to call for medical help.

What care does my child need?

After an infusion of methotrexate:

  • Your child will need continuous IV methotrexate for 24 hours. This will keep the medicine at a blood level that will kill cancer cells.
  • Your child will need continuous IV fluids.

Urine pH and methotrexate

Methotrexate is removed from the body by the kidneys. This works best when the urine’s pH (acid-base balance) is higher than 7. A urine pH less than 7 means the urine is too acidic. This may slow excretion or cause methotrexate crystals to form in the kidneys. This can cause damage to the kidneys or increase the side effects. To prevent kidney damage and increased side effects, IV fluids that have sodium bicarbonate in them are given. These fluids are started hours before the methotrexate is given.

    • Testing the urine pH

It is important to keep the pH of the urine between 7 and 8. We will need to test the urine every 6 hours. If the urine pH is below 7, your child will receive an additional dose of sodium bicarbonate.

Leucovorin rescue and methotrexate

Leucovorin is a medicine that rescues healthy cells from the effects of methotrexate. It will be started 42 hours after methotrexate starts to help neutralize the side effects of methotrexate on healthy cells.

The leucovorin is given every 6 hours. It is continued until the methotrexate levels are low enough in the body that the leucovorin isn’t needed and your child can be discharged. (See the education sheet “Leucovorin.”)

Methotrexate levels

After the infusion of methotrexate is completed, blood tests may be done to measure the level of methotrexate in the blood.

Are there any precautions about other medicines?

Some medicines can interfere with how the body processes the high dose methotrexate. Those medicines should not be given for 24 hours before starting chemotherapy until the IV fluids are stopped after the methotrexate infusion. The medicines to avoid are:

  • trimethoprim/sulfamethoxazole antibiotic (Bactrim®, Septran®, Co- trimoxazole®, SMX-TMP®)
  • non-steroidal medications: ibuprofen (Advil®), naproxen (Naprosyn®), aspirin
  • COX-2 inhibitors: rofecoxib (Vioxx®), celecoxib (Celebryx®)
  • fluroquinolone antibiotics: ciprofloxacin (Cipro®), gatifloxacin (Tequin®), levofloxacin (Levaquin®)
  • Proton pump inhibitors: Pantoprazole®

Because of all the IV fluids, your child should need to urinate more often. Remind your child to urinate every 3 to 4 hours and before going to bed at night. If your child is in diapers, check every 3 to 4 hours to be sure he or she is urinating often enough.Teeth should be brushed every morning and at bedtime. Check for reddened, sore spots on gums and inside cheeks. Children who have mouth sores may drool and refuse to swallow.

What precautions should I take?

All caregivers should wear gloves when handling urine, stool, and vomit while your child is getting the chemotherapy infusion and for 48 hours after it is completed.

Urine, stool, and vomit can be safely flushed in the sewer system and septic tanks.

Any clothing or bed linens that are contaminated with urine, stool, or vomit should be washed separately from other laundry in hot water and detergent. Anyone handling the contaminated laundry should wear gloves.

Who and when should I call for help?

Call hematology helpline 982403210 after discharge if:

  • vomiting more than once in 24 hours
  • diarrhea more than 3 times in 24 hours
  • mouth sores or mouth pain
  • fever higher than 101.5° F (38.6° C) by mouth
  • a dose of leucovorin is missed

Call 112 if:

  • trouble breathing
  • any other problems that you think need immediate attention


This sheet is not specific to your child but provides general information. If you have any questions, please call:

Hematology Clinic
3rd floor, Kedar
Opp.Krupa Petrol Pump,
Parimal Garden, Ambawadi
Clinic: 07926463219