Thyroid hormone replacement: what works, what to watch for
If your doctor said you need thyroid hormone replacement, you probably have a lot of questions. This page gives straightforward, practical info on the common drugs, how they’re used, and what to watch for so you can make informed decisions with your clinician.
The goal of replacement is simple: give your body the thyroid hormones it can’t make. Most people get levothyroxine (synthetic T4). Others need liothyronine (T3) or a mix. Some prefer natural desiccated thyroid (NDT) products that contain both T4 and T3.
Common options you'll hear about are Synthroid, Levoxyl, Tirosint (all levothyroxine brands), liothyronine (brand name Cytomel), and NDT brands like Armour or Nature‑Throid. Each option can work, but people react differently. That’s why treatment is personalized.
How doctors pick a medicine depends on blood tests and symptoms. TSH and free T4 are the usual labs. If TSH stays high on levothyroxine, your dose may need increasing. If symptoms persist despite normal labs, a doctor might consider adding T3 or switching formulations.
Dosing and monitoring
Take levothyroxine on an empty stomach, 30–60 minutes before breakfast, and keep it away from calcium or iron for several hours. Consistent timing and the same brand help keep levels steady. After any dose change, labs are usually checked in 6–8 weeks until levels and symptoms stabilize.
Too much thyroid hormone feels like racing heart, jitteriness, trouble sleeping, or unexplained weight loss. Too little causes fatigue, weight gain, cold sensitivity, and slow thinking. Report those signs—especially palpitations or chest pain—so your provider can act quickly.
Interactions, special situations, and switching
Many common substances affect absorption: calcium, iron, antacids, some cholesterol drugs and supplements like soy can lower levothyroxine uptake. Older adults, people with heart disease, and pregnant women need careful dosing and closer monitoring. If you switch brands or move from synthetic to NDT, expect retesting and dose adjustments.
Deciding between options often mixes science and preference. Some people prefer NDT for symptom relief; others do better on pure T4. There’s no universal best choice. Talk through risks and benefits with an endocrinologist or your primary care doctor.
If you buy medications online, check for a licensed pharmacy, clear contact info, and a requirement for a prescription. Our site includes guides on safe online pharmacies and alternatives to common brands so you can compare costs and reliability without risking fake or unsafe meds.
Want a quick win? Keep a list of your exact medication name, dose, when you take it, and any supplements. Bring that to appointments and lab visits. Small details like timing and calcium supplements make a big difference in how well replacement works.
If you're pregnant, planning pregnancy, or over 65, tell your doctor—targets and doses change. Keep medication list updated and bring lab results. If you feel worse after a change, call your provider. Our articles on Synthroid alternatives and safe online pharmacies can help you research options before making switches. Write down symptoms and their start dates too.
