Which common medicines can’t be taken with methotrexate (and why)?
Methotrexate can interact with several drug classes, mainly because other medicines can (1) increase methotrexate levels (raising toxicity risk) or (2) affect kidney clearance or folate pathways (increasing side effects such as mouth sores, low blood counts, or liver injury). The most important “avoid or closely manage” categories include:
NSAIDs (some situations)
Some NSAIDs can raise methotrexate exposure, especially in people with kidney problems or with higher-dose methotrexate. Many clinicians still use both in carefully selected patients with monitoring, but “don’t take together” rules often apply when kidney function is reduced or dosing is higher.
Antibiotics, especially trimethoprim-sulfamethoxazole (Bactrim/Septra)
Trimethoprim-sulfamethoxazole can further reduce folate activity alongside methotrexate, increasing the risk of severe low blood counts and other toxicity.
Certain seizure medicines
Some anti-seizure drugs can interact with methotrexate metabolism or protein binding. If you’re on an anticonvulsant, ask your prescriber/pharmacist before combining.
Other folate antagonists
Medicines that also block folate (for example, some cancer or infection therapies) can compound methotrexate’s folate effects.
Are there “no-go” medicines like antibiotics or antivirals?
Yes. People often get told to avoid or use extreme caution with:
- Trimethoprim-sulfamethoxazole (Bactrim/Septra) because of additive folate blockade and increased risk of blood and bone-marrow toxicity.
- Some other antibiotics that can affect methotrexate handling or increase toxicity risk.
Because antibiotic interactions depend on the specific drug and methotrexate dose (weekly low dose for rheumatoid arthritis/psoriasis vs. higher doses for cancer), the safest next step is to check any planned antibiotic with your pharmacist using your exact methotrexate regimen.
What about alcohol, liver-risk drugs, and supplements?
Methotrexate can strain the liver. Avoiding or minimizing alcohol is a common instruction, since alcohol increases the risk of liver injury. Also be cautious with other liver-harming drugs (certain acne medications, for example) and supplements that affect the liver.
If you share your other medications and supplements, I can help flag the typical high-risk categories to discuss with your clinician.
Can you take methotrexate with ibuprofen, naproxen, or aspirin?
It depends on your methotrexate dose and kidney function. In everyday practice, many people do use certain pain relievers while on low-dose weekly methotrexate, but clinicians are more cautious with:
- dehydration or kidney impairment,
- higher-dose methotrexate,
- older age,
- or frequent NSAID use.
If you tell me which NSAID and your methotrexate dose, I can narrow the likely level of concern.
Does folic acid change what you can take?
Folic acid is often prescribed with methotrexate to reduce side effects. It does not eliminate all drug-drug interaction risks, but it can reduce some methotrexate-related toxicity. Even with folic acid, you still generally avoid interacting medicines like trimethoprim-sulfamethoxazole unless your prescriber specifically approves and monitors you.
What signs mean you might be having a dangerous interaction?
If you develop any of these after starting a new medication or changing doses, seek urgent medical advice:
- mouth sores or severe sore throat,
- unusual bruising or bleeding,
- fever or signs of infection,
- severe nausea/vomiting or diarrhea,
- shortness of breath,
- yellowing of skin/eyes (liver problems),
- very dark urine or pale stools.
Fast way to get the exact answer for your prescription
Methotrexate interactions depend on:
- your methotrexate dose (weekly low-dose vs. cancer dosing),
- your kidney function,
- what other drugs you’re on (including OTC pain relievers),
- and whether you take folic acid.
If you paste your methotrexate dose (mg per week), and list the other medicines you’re considering (including OTCs and supplements), I can tell you which ones are commonly contraindicated vs. which ones are “sometimes used with monitoring.”
---
Sources
No reliable drug-interaction sources were provided with your question, so I can’t cite specific interaction lists. If you want, share the country you’re in and your methotrexate dose and I’ll format a precise “avoid vs. can be used with monitoring” list based on standard references.