Is Vitamin D Safe with Theophylline?
Free · No account · based on published sources including NIH ODS, FDA drug labels, and peer-reviewed literature
Maintain vitamin D supplementation within recommended daily limits (600–2000 IU/day). Inform your doctor of all supplements taken so theophylline levels can be monitored periodically.
Why this interaction occurs
Vitamin D influences CYP3A4 enzyme activity, which is partially involved in theophylline metabolism. High-dose vitamin D supplementation may modestly alter theophylline clearance. The clinical significance is generally low at standard supplement doses, but monitoring is prudent given theophylline's narrow therapeutic index.
Evidence
Evidence level: limited.
Reported safety data
The FDA’s adverse event reporting system (FAERS) has received 13,216 reports mentioning Theophylline. This reflects reported cases involving the medication in general — not confirmed causation, and not specific to the Theophylline + supplement combination on this page.
FAERS reports are voluntary and cannot prove that a drug caused an event. Do not use report counts to assess the safety of this specific drug-supplement pair.
Frequently asked questions
Related interactions
All Vitamin D interactions → · All Theophylline interactions →
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Educational only — not medical advice.
Always confirm with your doctor or pharmacist.