Once a Day is Not the Way if Once a Week is Enough


The story: Methotrexate is a cancer medicine. More recently, doctors have used it to treat other conditions like rheumatoid arthritis and psoriasis. It works well for these other conditions if you take the medicine just once or twice a week, and in smaller doses. But if you take it every day by accident, you could be harmed. Sadly, some people have even died.

In several instances, this happened because people misread the directions on the prescription bottle. In one case, a man with arthritis mistakenly took one tablet of methotrexate each morning, but the directions said to take one tablet each Monday. In another case, the prescription label said to take the medicine every 12 hours for just three doses. But a woman took the medicine every 12 hours for 6 days. Another woman took extra doses to help relieve her arthritis pain - something that should never be done.

The rest of the story: There are just a few medicines that you might take only once or twice a week. Methotrexate is one, if it's used to treat conditions other than cancer. Another example is Fosamax (alendronate), a medicine used to prevent or treat osteoporosis. While the 5 mg or 10 mg tablets should be taken daily, the 35 mg or 70 mg tablets should be taken once a week. Harmful mistakes may happen because you, your doctor, and your pharmacist are more familiar with medicines that are taken daily, not weekly. You could develop an ulcer if you take 35 mg or 70 mg tablets of Fosamax daily. Serious harm, even death, could occur if you take methotrexate daily for conditions other than cancer.

Lessons learned: In the future, we’re likely to see more medicines that can be taken once weekly, or less often. To avoid mistakes with medicines that should be taken weekly: When receiving a prescription — ask your doctor to put the reason for your medicine on all prescriptions. You might take a medicine like methotrexate daily if you have cancer, but weekly if you have arthritis. If the pharmacist knows your condition, he'll make sure the directions for taking your medicine are correct.

Ask your doctor if the medicine comes in a special package designed for weekly use. For example, Rheumatrex, one brand of methotrexate, comes in a weekly dose pack. Never leave the doctor's office unless you clearly understand how to take your medicine. When dropping off a prescription — pick the day(s) of the week that you'll be taking your medicine, and ask your pharmacist to include that in the instructions. Avoid Monday; it could be misread as morning. Ask for big print on the prescription label if you have poor eyesight. Ask the pharmacist to go over the directions for taking the medicine. Be sure it agrees with what the doctor told you. When taking your medicine never take any extra doses.

Created on January 1, 2004

Medication Safety Alerts

FDA Safety Alerts

Show Your Support!

ISMP needs your help to continue our life saving work