What the FDA labels say about taking them together
Histamine and theophylline
Histamine's FDA label of November 3, 2025 names theophylline in its drug interactions (prescription label) section; the theophylline label PlainMeds reads does not name histamine. The histamine label: “Short acting steroids, inhaled beta agonists, theophylline and cromolyn do not seem to affect skin test response.”
Check it at the source: the histamine FDA label on DailyMed (effective November 3, 2025); the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited).
What does the histamine label say about theophylline?
Histamine label, drug interactions (prescription label)Short acting steroids, inhaled beta agonists, theophylline and cromolyn do not seem to affect skin test response.
Source: FDA drug label (Histaminum hydrochloricum), Boiron, effective November 3, 2025 (SPL set 85b905d4-5fa3-7125-e053-2a91aa0a54f4), via openFDA; the full label on DailyMed
What does the theophylline label say about histamine?
Theophylline's label (effective March 10, 2026) does not name histamine in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Theophylline), Strides Pharma Science Limited, effective March 10, 2026 (SPL set b7a90ccf-9c32-40cc-9008-7e55b3da4dfd), 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
| Histamine | Theophylline | |
|---|---|---|
| Labeled for | n/a | Asthma |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.330 per tablet 300 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