What the FDA labels say about taking them together
Theophylline and varenicline
Varenicline's FDA label of January 23, 2026 names theophylline in its drug interactions section; the theophylline label PlainMeds reads does not name varenicline. The varenicline label: “Effect of Smoking Cessation on Other Drugs: Pharmacokinetics or pharmacodynamics of certain drugs may be altered, necessitating dose adjustment.”
Check it at the source: the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited); the varenicline FDA label on DailyMed (effective January 23, 2026, Pfizer Laboratories Div Pfizer Inc).
What does the theophylline label say about varenicline?
Theophylline's label (effective March 10, 2026) does not name varenicline 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
What does the varenicline label say about theophylline?
Varenicline label, drug interactionsEffect of Smoking Cessation on Other Drugs: Pharmacokinetics or pharmacodynamics of certain drugs (e.g., theophylline, warfarin, insulin) may be altered, necessitating dose adjustment.
Source: FDA drug label (CHANTIX), NDA021928 (Pf Prism Cv), as published by Pfizer Laboratories Div Pfizer Inc, effective January 23, 2026 (SPL set f0ff4f27-5185-4881-a749-c6b7a0ca5696), 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
| Theophylline | Varenicline | |
|---|---|---|
| Labeled for | Asthma | Quitting smoking |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | $0.330 per tablet 300 mg tablet | $0.316 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