Med of the Month: Methotrexate

Millions of people rely on methotrexate to manage conditions ranging from rheumatoid arthritis and psoriasis to certain types of cancer. While it's one of the most commonly prescribed immunosuppressive medications, it also has important implications for dental care. From oral mucosal manifestations and increased infection risk to significant drug interactions with medications dentists prescribe every day, methotrexate is one medication every dental professional should know well.

Generic Name: Methotrexate

Brand Name(s): Otrexup®, Rasuvo®, RediTrex®, Trexall®, Xatmep®

Pronunciation: meth oh TREX ate

About Methotrexate:

• Methotrexate is used to treat several kinds of cancer, including cancer of the blood, bone, lung, breast, head, and neck.

• It may also be used to treat rheumatoid arthritis and psoriasis.

Dentistry-related tidbits:

If you're treating a patient taking methotrexate, a few considerations are worth keeping in mind:

Local Anesthetic Warnings: At this time, there are no known restrictions for local anesthetics with or without epinephrine with methotrexate.

Oral Manifestations: 

• Methotrexate may cause thrombocytopenia and thromboembolism.

• Patients may also develop gingivitis, stomatitis, or oral mucositis. If painful oral ulcerations occur, "magic mouthwash" may help provide symptomatic relief.

Treatment Considerations:

• Patients taking methotrexate are at increased risk for infection due to immunosuppression. Refer the patient to their oncologist or emergency room if they exhibit signs of any type of infection.

• Follow a patient closely if they have a dental infection, have had dental surgery, and are taking this medication. Side effects include an increased risk for infection, worsening of an infection, and delayed wound healing.

• Avoid giving nitrous oxide to a patient taking methotrexate, as the combination may increase the risk of toxicity.

• This medication can pass into bodily fluids. If a patient should vomit during treatment, rubber gloves should be used to clean the patient's fluid and dispose of contaminated trash.

Staying Safe: important interactions to be aware of

Using a tool like MedAssent DDS Rx Check can help support safe prescribing and identify clinically relevant interactions.

Many medications commonly prescribed by dentists have serious drug interactions with methotrexate. It is generally recommended to speak with the patient's physician before prescribing any medications.

Some of the most clinically important interactions include:

• Combining the following medications with methotrexate may increase methotrexate levels and the risk of myelosuppression, serious infection, nephrotoxicity, and other side effects:

  • Penicillin antibiotics such as amoxicillin, ampicillin, dicloxacillin, penicillin G, penicillin V

  • Tetracycline antibiotics such as doxycycline, minocycline, tetracycline

  • Macrolide antibiotics such as azithromycin, erythromycin

  • Lincosamide antibiotic - clindamycin

  • Quinolone antibiotics such as ciprofloxacin, moxifloxacin

  • Cephalosporin antibiotics such as cephalexin, cefaclor

  • Nitroimidazole antibiotic - metronidazole

  • Antifungal - itraconazole

• Combining corticosteroids with methotrexate may increase the risk of serious infection, GI ulceration, perforation, and serious bleeding.

• Combining NSAIDs and aspirin with methotrexate may increase methotrexate levels and the risk of myelosuppression, serious infection, nephrotoxicity, and GI ulceration, perforation, and bleeding.

• Combining anticonvulsants (e.g. carbamazepine, gabapentin, pregabalin), benzodiazepines (e.g. clonazepam, diazepam, lorazepam, midazolam), or the narcotic tramadol with methotrexate may lower the seizure threshold.

Fun facts:

• Although originally developed as a chemotherapy medication, methotrexate is now most commonly prescribed in much lower doses to treat autoimmune diseases such as rheumatoid arthritis and psoriasis.

• Unlike most medications, methotrexate for autoimmune conditions is typically taken once weekly, not once daily. Taking it daily by mistake can result in serious toxicity.

• Methotrexate remains the first-line disease-modifying antirheumatic drug (DMARD) for many patients with rheumatoid arthritis because of its effectiveness and long track record.

• Many patients taking methotrexate for autoimmune diseases are also prescribed folic acid to help reduce side effects such as mouth sores and gastrointestinal upset without reducing the medication's effectiveness.

Get more dental-specific drug information with the Digital Drug Handbook (web) or BrushUp Rx (mobile app).