NSAID (phenylacetic acid)
Diclofenac with thyroid medication (levothyroxine)
Levothyroxine is one of the most prescribed medications worldwide, and many adults on it also use chronic medications such as Diclofenac (Diclofenac). 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 25mg, 50mg, 75mg, 100mg.
How Diclofenac affects thyroid medication
Levothyroxine absorption is sensitive to timing relative to food, calcium, iron and several medications. Whether Diclofenac interferes depends on Diclofenac — most agents in NSAID (phenylacetic acid) have no clinically meaningful effect on thyroid hormone levels, but a small number affect TSH or T4 free fraction. Diclofenac reversibly inhibits cyclooxygenase enzymes COX-1 and COX-2, with somewhat greater selectivity for COX-2 than ibuprofen and naproxen.
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. Diclofenac at 25mg, 50mg, 75mg, 100mg can usually be taken at any time relative to the levothyroxine dose, but the prescribing information for Diclofenac should be checked for specific timing instructions.
Frequently asked questions
Will Diclofenac affect my thyroid levels? ▾
Most NSAID (phenylacetic acid) medications do not directly affect thyroid hormone levels at 25mg, 50mg, 75mg, 100mg. 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 Diclofenac relative to levothyroxine? ▾
Levothyroxine is taken on an empty stomach with at least a 30-minute fast and 4-hour separation from interacting medications. Diclofenac at 25mg, 50mg, 75mg, 100mg usually has no specific timing constraint relative to levothyroxine; the pharmacist confirms based on the prescribing information for Diclofenac.
Products containing Diclofenac
More on Diclofenac
- With alcoholDiclofenac and alcohol — is it safe to drink?
- With foodShould Diclofenac be taken with food?
- Side effectsDiclofenac side effects: common, rare and warning signs
- Dosage guideDiclofenac dosage guide: how much to take and when
- OnsetHow fast does Diclofenac start working?
- DurationHow long does Diclofenac last?
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