What the FDA labels say about taking them together
Levocetirizine and theophylline
Levocetirizine's FDA label of March 11, 2026 names theophylline in its drug interactions (prescription label) section; the theophylline label PlainMeds reads does not name levocetirizine. The levocetirizine label: “There was a small decrease (~16%) in the clearance of cetirizine caused by a 400 mg dose of theophylline.”
Check it at the source: the levocetirizine FDA label on DailyMed (effective March 11, 2026, Chattem, Inc.); the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited).
What does the levocetirizine label say about theophylline?
Levocetirizine label, drug interactions (prescription label)There was a small decrease (~16%) in the clearance of cetirizine caused by a 400 mg dose of theophylline.
Source: FDA drug label (Xyzal Allergy 24HR), Chattem, Inc., effective March 11, 2026 (SPL set 8be45c2a-1eca-4a00-81b9-f7babdbdcd41), via openFDA; the full label on DailyMed
What does the theophylline label say about levocetirizine?
Theophylline's label (effective March 10, 2026) does not name levocetirizine 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
| Levocetirizine | Theophylline | |
|---|---|---|
| Labeled for | Allergies | Asthma |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.0511 per tablet 5 mg tablet | $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