What the FDA labels say about taking them together
Cycloserine and folic acid
Folic acid's FDA label (Folic Acid) of February 11, 2026 names cycloserine in its drug interactions section; the cycloserine 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 cycloserine FDA label on DailyMed (effective July 30, 2024, Dr. Reddys Laboratories, Inc.); the folic acid FDA label on DailyMed (effective July 24, 2026, Rising Pharma Holdings, Inc.).
What does the cycloserine label say about folic acid?
Cycloserine's label (effective July 30, 2024) 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 (Cycloserine), ANDA060593 (Sanaluz), as published by Dr. Reddys Laboratories, Inc., effective July 30, 2024 (SPL set 8e7e2665-7a3d-3f54-9f92-5fe845f02ef9), via openFDA; the full label on DailyMed
What does the folic acid label say about cycloserine?
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
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
| Cycloserine | Folic acid | |
|---|---|---|
| Labeled for | Bacterial infections, Urinary tract infections | n/a |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.0201 per tablet 1 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