Drug interactions
Levothyroxine + Theophylline
Severity: Minor
Levothyroxine 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
Thyroid status changes theophylline clearance: hyperthyroid states speed it up and hypothyroid states slow it down. Starting levothyroxine in a hypothyroid patient can therefore increase theophylline clearance and lower serum levels over time.
What this interaction means in plain words
Levothyroxine 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.
Levothyroxine belongs to Endocrine; Theophylline belongs to Respiratory.
Why it happens
Restoring a euthyroid state raises hepatic metabolic capacity and increases theophylline clearance.
What to do
When thyroid replacement is started or the dose changed in a patient on theophylline, check theophylline serum levels and adjust the dose if needed.
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
Other interactions of Levothyroxine
Frequently asked questions
Can I take Levothyroxine with Theophylline?
MediHelp rates the interaction as minor. Levothyroxine 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. Thyroid status changes theophylline clearance: hyperthyroid states speed it up and hypothyroid states slow it down. Starting levothyroxine in a hypothyroid patient can therefore increase theophylline clearance and lower serum levels over time.
How serious is the interaction between Levothyroxine 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: When thyroid replacement is started or the dose changed in a patient on theophylline, check theophylline serum levels and adjust the dose if needed.
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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