Not at the same time — iron blocks levothyroxine absorption, so you can take both but must separate them by at least 4 hours and confirm timing with your pharmacist.
Iron (such as ferrous sulfate) binds to levothyroxine in the gut, forming a poorly absorbed complex that reduces how much thyroid hormone reaches your bloodstream, which can make the levothyroxine work less well. Both MedlinePlus (the NIH/FDA-sourced drug page) and the NHS list iron salts among the substances that interfere with levothyroxine absorption when taken together. This is a real, clinically meaningful interaction — it does not make the pair forbidden, but taking them simultaneously can leave your hypothyroidism undertreated. Levothyroxine is normally taken once daily on an empty stomach, 30 to 60 minutes before breakfast.
Take levothyroxine first thing on an empty stomach, then take your iron at least 4 hours before or after it (MedlinePlus specifies a 4-hour gap; the NHS says to space them out and check with your pharmacist) — most people take levothyroxine in the morning and iron in the afternoon or evening. The same 4-hour separation applies to calcium, antacids, and multivitamins that contain iron or calcium. Tell your doctor and pharmacist about all supplements; if you start or stop iron, ask about rechecking your thyroid blood tests (TSH), since dosing may need adjustment. Watch for signs your thyroid medication isn't working well enough — fatigue, weight gain, feeling cold, or low mood — and contact your clinician if they appear. Do not change your levothyroxine dose on your own.
This is general reference, not medical advice, and not a guarantee of safety. Interactions depend on your doses, health conditions, and other medicines. Always confirm with your pharmacist or doctor before combining products, and follow the dosing on each label.