Drug interactions
Phytoestrogens + Theophylline
Severity: Minor
Phytoestrogens and Theophylline: minor interaction.
Last updated
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Isoflavones such as daidzein have been shown to inhibit CYP1A2 and raise theophylline levels in some studies. Higher levels could cause toxicity, mainly with high-dose supplements.
What this interaction means in plain words
Phytoestrogens and Theophylline have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Phytoestrogen isoflavones inhibit CYP1A2, reducing theophylline metabolism.
What to do
Monitor theophylline levels and toxicity signs if high-dose isoflavone supplements are started or stopped.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Theophylline
- Riociguat + Theophylline Contraindicated
- Adenosine + Theophylline Major
- Apalutamide + Theophylline Major
- Bupropion + Theophylline Major
- Carvedilol + Theophylline Major
- Cimetidine + Theophylline Major
Frequently asked questions
Can I take Phytoestrogens with Theophylline?
MediHelp rates the interaction as minor. Phytoestrogens and Theophylline have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Isoflavones such as daidzein have been shown to inhibit CYP1A2 and raise theophylline levels in some studies. Higher levels could cause toxicity, mainly with high-dose supplements.
How serious is the interaction between Phytoestrogens and Theophylline?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor theophylline levels and toxicity signs if high-dose isoflavone supplements are started or stopped.
What other medicines interact with Theophylline?
MediHelp also lists interactions of Theophylline with, for example, Riociguat, Adenosine, Apalutamide. The full list is on the Theophylline page.
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