Atypical antidepressant (NaSSA)
Mirtazapine with thyroid medication (levothyroxine)
Levothyroxine is one of the most prescribed medications worldwide, and many adults on it also use chronic medications such as Mirtazapine (Mirtazapine). The combination is generally safe, but levothyroxine's narrow therapeutic index and finicky absorption mean a few practical points matter more than for most other co-administered drugs at 7.5mg, 15mg, 30mg, 45mg.
How Mirtazapine affects thyroid medication
Levothyroxine absorption is sensitive to timing relative to food, calcium, iron and several medications. Whether Mirtazapine interferes depends on Mirtazapine — most agents in Atypical antidepressant (NaSSA) have no clinically meaningful effect on thyroid hormone levels, but a small number affect TSH or T4 free fraction. Mirtazapine antagonises presynaptic α2-adrenergic autoreceptors and heteroreceptors, increasing noradrenaline and serotonin release.
Practical timing
According to standard endocrine practice, levothyroxine is taken on an empty stomach at least 30 minutes before food and 4 hours from interacting medications. Mirtazapine at 7.5mg, 15mg, 30mg, 45mg can usually be taken at any time relative to the levothyroxine dose, but the prescribing information for Mirtazapine should be checked for specific timing instructions.
Frequently asked questions
Will Mirtazapine affect my thyroid levels? ▾
Most Atypical antidepressant (NaSSA) medications do not directly affect thyroid hormone levels at 7.5mg, 15mg, 30mg, 45mg. Some affect TSH testing, hormone-binding proteins or T4 free fraction in subtle ways. Routine thyroid function tests every few months catch any meaningful drift.
When should I take Mirtazapine relative to levothyroxine? ▾
Levothyroxine is taken on an empty stomach with at least a 30-minute fast and 4-hour separation from interacting medications. Mirtazapine at 7.5mg, 15mg, 30mg, 45mg usually has no specific timing constraint relative to levothyroxine; the pharmacist confirms based on the prescribing information for Mirtazapine.
Products containing Mirtazapine
More on Mirtazapine
- With alcoholMirtazapine and alcohol — is it safe to drink?
- With foodShould Mirtazapine be taken with food?
- Side effectsMirtazapine side effects: common, rare and warning signs
- Dosage guideMirtazapine dosage guide: how much to take and when
- OnsetHow fast does Mirtazapine start working?
- DurationHow long does Mirtazapine last?
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