Methotrexate dosage is different from that of other medications in that you only take it once a week.
That can be confusing, especially if your healthcare provider or pharmacist haven’t explained it.
It’s used off-label (without FDA approval) for several other diseases in this category.
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Methotrexate calms the immune system and lessens the attack.
It commonly strikes the hands, wrists, and knees but can target any joint.
Some people with RA develop systemic disease, meaning the immune system targets organs or systems throughout the body.
Common targets are the eyes, heart, and lungs.
The oral (tablet) form of methotrexate is typically prescribed for RA.
The injectable form may be used if you have trouble swallowing the pills.
Psoriatic Disease
Psoriatic disease includes plaque psoriasis and psoriatic arthritis.
Methotrexate is used for both of these conditions.
The result is thick, scaly patches that may itch or be quite painful.
On light skin, it’s usually red with white or silvery scales.
Psoriatic Arthritis
Psoriatic arthritis (PsA) involves both psoriasis and joint pain.Methotrexate is given off-label for PsA.
(“Polyarticular” means “many joints.")
Healthcare providers calculate the pediatric methotrexate dosage based on the child’s body weight.
Common targets include:
Methotrexate is prescribed off-label for SLE.
The weekly dosage depends on whether it’s given as a pill or injection.
In one study, 80% of kids responded to the 5 mg or 10 mg dosage.
But it can affect any part of the digestive system.
For Crohn’s, methotrexate is typically used in addition to other medications.
Methotrexate Dosage for Other Uses
Methotrexate was a cancer drug before it was approved for rheumatoid arthritis.
It’s also used to treat ectopic pregnancies.
Both these uses stem from methotrexate’s ability to stop certain cells from growing.
Acute Lymphocytic Leukemia
Acute lymphocytic leukemia (ALL) is a blood cancer.
It causes rapid overgrowth of immature white blood cells called lymphocytes.
After starting in the bone marrow, it quickly invades the bloodstream and possibly other organs and systems.
For ALL, the methotrexate dosage is weight-based.
It’s part of a chemotherapy regimen involving several drugs.
It may be given in intramuscular injections, or, especially for higher doses, intravenously (IV).
The schedule and dosage depend on the disease state and many other factors.
It may be given more or less frequently than once a week.
Starting maintenance dosages are:
The maintenance dosage may be adjusted based on lab test and other factors.
Each cancer bang out has its own dosage guidelines.
As the fetus grows, the fallopian tube generally ruptures.
This can cause life-threatening internal bleeding and emergency surgery is required.
So far, doctors are unable to re-implant a fetus developing ectopically to a uterus or other location.
The pregnancy is always lost.
Some ectopic pregnancies are removed surgically.
Others are treated with methotrexate because it stops cells from growing.
The body can then absorb the pregnancy over the next several weeks.
Methotrexate injections are used for ectopic pregnancies.
Your doctor may also switch you to a subcutaneous (under the skin) injection.
Methotrexate Warnings
Methotrexate comes with several important warnings.
Paying attention to these can help you avoid problems or spot them early.
Methotrexate and Pregnancy
Methotrexate is dangerous during pregnancy and breastfeeding.
Methotrexate can cause:
Your healthcare provider should go over these risks with you before prescribing methotrexate.
verify your healthcare provider and pharmacist have a complete list of your medications, both prescription and over-the-counter.
Don’t wait to see if symptoms go away on their own.
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