If you have hypothyroidism or another thyroid issue, the right medicine and the right routine make a big difference. This page covers the common drugs, how to take them, what affects their action, and quick tips for safer use.
Most patients start with levothyroxine (T4). It's stable, long‑acting, and the usual choice for low thyroid function. Some people need liothyronine (T3) or a combination when symptoms persist despite normal labs. Desiccated thyroid extract is another option; it contains both T3 and T4, but dosing is less predictable. Your doctor will pick the best option based on symptoms, blood tests, age, pregnancy plans, and other health issues.
Take levothyroxine on an empty stomach, 30–60 minutes before breakfast, or at least four hours after your last meal if you prefer evening dosing. Stick to one schedule — switching morning to evening can change blood levels. Use the same brand or generic if possible; changes can require rechecking your thyroid-stimulating hormone (TSH). Swallow with plain water. Avoid crushing tablets unless your provider says it's safe.
Space out supplements and common interactors. Calcium, iron, magnesium, and multivitamins can lower absorption if taken within four hours. Soy products and high‑fiber meals may also affect uptake. If you take calcium or iron, take them at a different time of day.
Get TSH checked 6–8 weeks after starting or changing dose. That’s how clinicians find the right number for you. Pregnant people need higher doses early in pregnancy; discuss this with your provider as soon as you get a positive test. Older adults and those with heart disease often start at a lower dose to avoid overstimulation of the heart.
Watch for signs of over- or under‑treatment. Symptoms of too much thyroid hormone include palpitations, weight loss, tremor, and anxiety. Too little leads to fatigue, weight gain, cold sensitivity, and constipation. If symptoms change, tell your clinician — don’t adjust the dose on your own.
If your pharmacy switches brands or you change from brand to generic, recheck TSH in 6–8 weeks. Some people also need free T4 and free T3 checked if symptoms don't match TSH. Autoimmune causes like Hashimoto's are diagnosed with thyroid peroxidase (TPO) antibodies. Once your dose is stable, annual checks are common, but check sooner if you get sick, start new meds, or change weight. Keep a log of symptoms and doses — it helps clinicians.
If you buy meds online, use licensed pharmacies and require a prescription. Avoid sites that sell without a prescription or offer suspiciously low prices. Keep medications in a dry, cool place away from sunlight. If you miss a dose, take it as soon as you remember the same day; don’t double the next day.
Finally, discuss any other drugs you take — antacids, proton pump inhibitors, cholesterol medicines, and some antidepressants can interact. Clear communication with your provider speeds dose finding and keeps you feeling better sooner.
