How long does methotrexate stay in your system?

How long after stopping Methotrexate will it be in my system?

The estimated length of time it takes for methotrexate to be removed from your body is:

• For low dose methotrexate ranges from 16.5 hours to 55 hours.
• For high dose methotrexate ranges from 44 hours to 82.5 hours.

The length of time it takes for a medicine to be removed from your body depends on the drug's elimination half-life. It takes 5.5 x elimination half-life for most of a medicine to be removed from your system.

For low dose methotrexate the half life range is 3 to 10 hours so

• 3 hours X 5.5 = 16.5 hours.
• 10 hours X 5.5 hours = 55 hours.
• Therefore for the estimated elimination time range for low dose methotrexate is 16.5 hours to 55 hours.

For high dose methotrexate the half life range is 8 to 15 hours so

• 8 hours X 5.5 hours = 44 hours.
• 15 hours X 5.5 hours = 82.5 hours.
• Therefore the estimated elimination time range for high dose methotrexate is 44 hours to 82.5 hours.

Elimination times are an estimate and can vary due to patient-specific variables and drug-specific variables including:

• How much and how often you have taken the drug.
• Your metabolic rate – a slower metabolism will increase the time a drug remains in your system and a faster metabolism will decrease the time a drug remains in your system.
• Your age and health issues – older age and poor health may change the time the drug says in your system.
• Body mass.
• Drug formulation, way of administration, pharmacokinetics, volume of distribution etc.