What the FDA labels say about taking them together
Dexamethasone and isoniazid
Dexamethasone's FDA label of June 6, 2025 names isoniazid in its drug interactions section; the isoniazid label PlainMeds reads does not name dexamethasone. The dexamethasone label: “Antitubercular drugs: Serum concentrations of isoniazid may be decreased.”
Check it at the source: the dexamethasone FDA label on DailyMed (effective June 6, 2025, Hikma Pharmaceuticals USA, Inc.); the isoniazid FDA label on DailyMed (effective July 8, 2025, OMNIVIUM PHARMACEUTICALS LLC.).
What does the dexamethasone label say about isoniazid?
Dexamethasone label, drug interactionsAntitubercular drugs: Serum concentrations of isoniazid may be decreased.
Hemady label (Edenbridge Pharmaceuticals LLC., January 9, 2026), drug interactionsIsoniazid Serum concentrations of isoniazid may be decreased with corticosteroids.
Source: FDA drug label (Hemady, NDA211379), Edenbridge Pharmaceuticals LLC., effective January 9, 2026 (SPL set 6b9cf32c-6d60-4853-bbfd-2304ffc2c129), via openFDA
Source: FDA drug label (Dexamethasone Intensol), Hikma Pharmaceuticals USA, Inc., effective June 6, 2025 (SPL set b15200fb-1826-472b-a907-e677a272513b), via openFDA; the full label on DailyMed
What does the isoniazid label say about dexamethasone?
Isoniazid's label (effective July 8, 2025) does not name dexamethasone in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (isoniazid), OMNIVIUM PHARMACEUTICALS LLC., effective July 8, 2025 (SPL set 35400f1d-fd25-4bfa-a382-ac390e21bf2e), 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
| Dexamethasone | Isoniazid | |
|---|---|---|
| Labeled for | Asthma, Eczema (atopic dermatitis), Leukemia, lymphoma and myeloma, Herpes and shingles, Crohn's disease and ulcerative colitis, Multiple sclerosis, Osteoarthritis, Rheumatoid arthritis, Psoriasis, Allergies, Anemia, Pain | n/a |
| Boxed warning | No | Yes |
| Pharmacy cost (NADAC) | $0.193 per tablet 4 mg tablet | $3.40 per tablet 300 mg tablet |
| Shortage now | In shortage | 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