Thyroid medication: avoid calcium and get better absorption — August 2024

If you take thyroid medicine, small habits can change how well it works. In August 2024 we highlighted Dr. Keith Roach’s clear, practical advice: take your thyroid pill on an empty stomach and keep calcium away for a while. That simple routine helps your body actually absorb the drug instead of letting it sit unused.

Why does calcium matter? Calcium binds to common thyroid drugs like levothyroxine and lowers how much gets into your bloodstream. If that happens regularly, your lab results and symptoms can drift even if you’re taking the same dose. Fixing timing is easy and often solves the problem without changing your prescription.

Practical timing rules you can start today

Follow a consistent schedule. Dr. Roach recommends taking your thyroid pill first thing in the morning on an empty stomach, then waiting at least one hour before eating or taking other medicines. That gives the drug time to start absorbing. If you need to take calcium supplements, try to take them several hours later — many clinicians suggest a 4-hour gap for supplements or antacids that contain calcium.

If mornings are chaotic, you can also take thyroid medicine at bedtime. Pick a time at least three to four hours after your last meal and stick to it every day. The key is consistency: take it the same way every day so your lab tests reflect a steady pattern, not random ups and downs.

Simple checks and tips to avoid slip-ups

Read labels — some multivitamins and antacids hide calcium. If you use a multivitamin, move it to midday or evening. Tell your pharmacist and doctor about all supplements and over-the-counter meds so they can spot hidden calcium sources. If you take iron or calcium, separate them from your thyroid pill by several hours.

Watch your labs. If your TSH or symptoms change after starting supplements or a new routine, ask for a blood test. Small timing changes can look like your dose needs adjusting, but often it’s just an absorption issue. Before changing dose, confirm with a lab done while you follow your usual timing.

Quick checklist: take thyroid pill on empty stomach, wait at least 1 hour before food, move calcium supplements 3–4 hours away, consider bedtime dosing if mornings don’t work, and tell your provider about vitamins and antacids. These steps follow Dr. Roach’s advice and are easy to try right away.

If you’re unsure what’s best for you, ask your doctor. They'll help you choose timing that fits your life and arrange the right tests so your treatment stays on track.