What the FDA labels say about taking them together
Folic acid and sulfasalazine
Folic acid's FDA label (Folic Acid) of February 11, 2026 names sulfasalazine in its drug interactions section; the sulfasalazine label PlainMeds reads does not name folic acid. The folic acid label: “Valproate and sulfasalazine primarily reduce intestinal folate absorption or interfere with folate-dependent metabolic pathways, while isoniazid and cycloserine reduce folate utilization through metabolic disruption.”
Check it at the source: the folic acid FDA label on DailyMed (effective July 24, 2026, Rising Pharma Holdings, Inc.); the sulfasalazine FDA label on DailyMed (effective May 29, 2026, Pfizer Laboratories Div Pfizer Inc).
What does the folic acid label say about sulfasalazine?
Folic Acid label (Ayurax, LLC, February 11, 2026), drug interactionsValproate and sulfasalazine primarily reduce intestinal folate absorption or interfere with folate-dependent metabolic pathways, while isoniazid and cycloserine reduce folate utilization through metabolic disruption.
Source: FDA drug label (Folic Acid, NDA216395), Ayurax, LLC, effective February 11, 2026 (SPL set 96618bf8-6c03-4df3-9896-b7ef27ca392a), via openFDA
Source: FDA drug label (Folic Acid), Rising Pharma Holdings, Inc., effective July 24, 2026 (SPL set 0baa10dd-6d1d-4946-8236-566451132da3), via openFDA; the full label on DailyMed
What does the sulfasalazine label say about folic acid?
Sulfasalazine's label (effective May 29, 2026) does not name folic acid in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Azulfidine), Pfizer Laboratories Div Pfizer Inc, effective May 29, 2026 (SPL set ddbe69f3-bd55-45f3-a64f-f60226c744c4), via openFDA; the full label on DailyMed
These are the labels' own sentences. PlainMeds does not grade interactions; a pharmacist or prescriber can say what they mean for one person's medicines.
Both medicines on the record
| Folic acid | Sulfasalazine | |
|---|---|---|
| Labeled for | n/a | Crohn's disease and ulcerative colitis, Rheumatoid arthritis |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0201 per tablet 1 mg tablet | $0.199 per tablet 500 mg tablet |
| Shortage now | No current entry | No current entry |
Source: FDA NDC Directory, CMS NADAC of October 7, 2026 and the FDA Drug Shortage Database (FDA files October 8, 2026)
What next?
- Check more medicines together
- up to five at once