Drug interactions
Carbamazepine + Levothyroxine
Severity: Moderate
Carbamazepine and Levothyroxine: moderate 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
Carbamazepine can increase levothyroxine clearance and lower thyroid hormone levels, potentially causing hypothyroidism or reduced control in treated patients. It can also lower total T4 even in euthyroid patients.
What this interaction means in plain words
Carbamazepine and Levothyroxine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Carbamazepine belongs to Central Nervous System; Levothyroxine belongs to Endocrine.
Why it happens
Carbamazepine induces hepatic glucuronidation and metabolism of thyroid hormones.
What to do
Monitor TSH and free T4 about 6 to 8 weeks after starting or stopping carbamazepine. Increase the levothyroxine dose if needed.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Carbamazepine
- Artemether / lumefantrine + Carbamazepine Contraindicated
- Cabotegravir + Carbamazepine Contraindicated
- Carbamazepine + Delamanid Contraindicated
- Carbamazepine + Dienogest / estradiol valerate Contraindicated
- Carbamazepine + Doravirine Contraindicated
- Carbamazepine + Elbasvir / grazoprevir Contraindicated
Other interactions of Levothyroxine
Frequently asked questions
Can I take Carbamazepine with Levothyroxine?
MediHelp rates the interaction as moderate. Carbamazepine and Levothyroxine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Carbamazepine can increase levothyroxine clearance and lower thyroid hormone levels, potentially causing hypothyroidism or reduced control in treated patients. It can also lower total T4 even in euthyroid patients.
How serious is the interaction between Carbamazepine and Levothyroxine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor TSH and free T4 about 6 to 8 weeks after starting or stopping carbamazepine. Increase the levothyroxine dose if needed.
What other medicines interact with Carbamazepine?
MediHelp also lists interactions of Carbamazepine with, for example, Artemether / lumefantrine, Cabotegravir, Delamanid. The full list is on the Carbamazepine page.
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