Drug interactions
Furosemide + Levothyroxine
Severity: Minor
Furosemide and Levothyroxine: 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
High doses of furosemide can displace thyroid hormones from binding proteins, causing a brief rise in free hormone followed by lower total hormone levels. This can confuse thyroid function test interpretation but rarely causes clinical toxicity.
What this interaction means in plain words
Furosemide and Levothyroxine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Furosemide belongs to Cardiovascular; Levothyroxine belongs to Endocrine.
Why it happens
Furosemide competes with thyroid hormone for plasma protein binding sites.
What to do
Interpret thyroid function tests cautiously in patients receiving high-dose furosemide, particularly intravenously. Adjust levothyroxine only on the basis of clinical status and repeated TSH.
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 Furosemide
- Amifostine + Furosemide Major
- Amikacin + Furosemide Major
- Carbenoxolone + Furosemide Major
- Cephaloridine + Furosemide Major
- Cisplatin + Furosemide Major
- Digoxin + Furosemide Major
Other interactions of Levothyroxine
Frequently asked questions
Can I take Furosemide with Levothyroxine?
MediHelp rates the interaction as minor. Furosemide and Levothyroxine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. High doses of furosemide can displace thyroid hormones from binding proteins, causing a brief rise in free hormone followed by lower total hormone levels. This can confuse thyroid function test interpretation but rarely causes clinical toxicity.
How serious is the interaction between Furosemide and Levothyroxine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Interpret thyroid function tests cautiously in patients receiving high-dose furosemide, particularly intravenously. Adjust levothyroxine only on the basis of clinical status and repeated TSH.
What other medicines interact with Furosemide?
MediHelp also lists interactions of Furosemide with, for example, Amifostine, Amikacin, Carbenoxolone. The full list is on the Furosemide page.
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