What the FDA labels say about taking them together
Peginterferon alfa 2a and theophylline
Peginterferon alfa 2a's FDA label of September 2, 2026 names theophylline in its drug interactions section; the theophylline label PlainMeds reads does not name peginterferon alfa 2a. The peginterferon alfa 2a label: “DRUG INTERACTIONS Drugs metabolized by CYP1A2: monitor for increased serum levels of theophylline and adjust dose accordingly Methadone: monitor for signs and symptoms of methadone toxicity Nucleoside analogues: closely …”
Check it at the source: the peginterferon alfa 2a FDA label on DailyMed (effective September 2, 2026); the theophylline FDA label on DailyMed (effective March 10, 2026, Strides Pharma Science Limited).
What does the peginterferon alfa 2a label say about theophylline?
Peginterferon alfa 2a label, drug interactionsDRUG INTERACTIONS Drugs metabolized by CYP1A2: monitor for increased serum levels of theophylline and adjust dose accordingly ( 7.2 ) Methadone: monitor for signs and symptoms of methadone toxicity ( 7.3 ) Nucleoside analogues: closely monitor for toxicities.
Source: FDA drug label (Pegasys), pharmaand GmbH, effective September 2, 2026 (SPL set d9290e5b-6d40-2318-e053-2995a90a9916), via openFDA; the full label on DailyMed
What does the theophylline label say about peginterferon alfa 2a?
Theophylline's label (effective March 10, 2026) does not name peginterferon alfa 2a 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
| Peginterferon alfa 2a | Theophylline | |
|---|---|---|
| Labeled for | Hepatitis C, Hepatitis B | Asthma |
| Boxed warning | Yes | No |
| Pharmacy cost (NADAC) | n/a | $0.330 per tablet 300 mg tablet |
| Shortage now | Resolved | 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