What the FDA labels say about taking them together
Aminophylline and cimetidine
Aminophylline's FDA label of May 22, 2026 names cimetidine in its drug interactions section; the cimetidine label PlainMeds reads does not name aminophylline. The aminophylline label: “Drug: Cimetidine; Type Of Interaction: Decreases theophylline clearance by inhibiting cytochrome P450 1A2.; Effect**: 70% increase”
Check it at the source: the aminophylline FDA label on DailyMed (effective May 22, 2026, Hospira, Inc.); the cimetidine FDA label on DailyMed (effective July 15, 2026, Mylan Pharmaceuticals Inc.).
What does the aminophylline label say about cimetidine?
Aminophylline label, drug interactionsDrug: Cimetidine; Type Of Interaction: Decreases theophylline clearance by inhibiting cytochrome P450 1A2.; Effect**: 70% increase
Aminophylline label, warningsAge Neonates (term and premature) Children <1 year Elderly (>60 years) Concurrent Diseases Acute pulmonary edema Congestive heart failure Cor pulmonale Fever; ≥102° for 24 hours or more; or lesser temperature elevations for longer periods Hypothyroidism Liver disease; cirrhosis, acute hepatitis Reduced renal function in infants <3 months of age Sepsis with multi-organ failure Shock Cessation of Smoking Drug Interactions Adding a drug that inhibits theophylline metabolism (e.g., cimetidine, erythromycin, tacrine) or stopping a concurrently administered drug that enhances theophylline metabolism (e.g., carbamazepine, rifampin) (see PRECAUTIONS , Drug Interactions, Table II ).
Source: FDA drug label (Aminophylline), Hospira, Inc., effective May 22, 2026 (SPL set 9a663ef3-881f-48bd-2689-3713b24545c2), via openFDA; the full label on DailyMed
What does the cimetidine label say about aminophylline?
Cimetidine's label (effective July 15, 2026) does not name aminophylline in these sections. A label lists what its studies and reports found; it is not a complete list.
Source: FDA drug label (Cimetidine), Mylan Pharmaceuticals Inc., effective July 15, 2026 (SPL set 06c0a509-026f-44e0-9975-a94a8de51d43), 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
| Aminophylline | Cimetidine | |
|---|---|---|
| Labeled for | Asthma | Acid reflux and ulcers |
| Boxed warning | No | No |
| Pharmacy cost (NADAC) | n/a | $0.236 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