Can a Copper IUD Cause Thyroid Issues?
No, there is no evidence that copper IUDs cause thyroid dysfunction or thyroid-related problems. The available medical guidelines and research do not identify thyroid issues as a recognized side effect or complication of copper IUD use.
What the Evidence Shows
Documented Side Effects of Copper IUDs
The established side effects of copper IUDs are well-characterized and do not include thyroid dysfunction:
Menstrual changes: Increased bleeding and pain during menses are the most common side effects, with most bleeding and pain complaints decreasing over time during the first year of use 1
Hematologic effects: Copper IUDs can cause decreased serum iron and reduced transferrin saturation, particularly with long-term use, though mean hemoglobin levels typically remain stable 2
Trace metal changes: Copper IUD use causes a slight elevation in serum copper levels (from 160.40 μg/dl at baseline to 170.22 μg/dl at 3 months), but these levels do not reach toxic ranges 3
Infection risk: The primary serious complication is pelvic inflammatory disease, which occurs mainly in the first 20-21 days after insertion, particularly in women with active STIs 4, 5
Contraindications Do Not Include Thyroid Disease
Major medical organizations have established clear contraindications for copper IUD use, and thyroid disorders are notably absent:
Absolute contraindications: Only pregnancy is listed as an absolute contraindication (Category 4) 6
Relative contraindications: Active STIs (chlamydia or gonorrhea) are Category 3 contraindications 6
No thyroid-related restrictions: Neither hypothyroidism nor hyperthyroidism appears in any medical eligibility criteria for copper IUD use 4, 6, 5
Clinical Implications
If a patient with a copper IUD develops thyroid symptoms, the IUD is not the cause and should not be removed for this indication. The thyroid issue requires standard evaluation and management independent of contraceptive choice. The copper IUD can safely remain in place during thyroid disease diagnosis and treatment, as there are no documented interactions between copper IUDs and thyroid function 4.