Synthroid (Levothyroxine) – What It Is, How It Works, and What You Need to Know

If your doctor prescribed Synthroid, you’re probably dealing with an under‑active thyroid, also called hypothyroidism. Synthroid is a brand name for levothyroxine, a synthetic version of the hormone your thyroid normally makes. The goal is to bring your hormone levels back to normal so you feel more energetic, avoid weight gain, and keep your heart and metabolism on track.

Most people take Synthroid once a day, usually in the morning, on an empty stomach. It’s absorbed best when you wait at least 30 minutes before eating or drinking anything except water. Skipping doses or taking them at different times can make your symptoms swing back and forth, so consistency matters.

When to Take Synthroid and How to Dose It

Doctors start you on a low dose and adjust it based on blood tests that measure TSH (thyroid‑stimulating hormone). The right dose varies a lot—some need just 25 µg, others need 200 µg or more. Never change the dose on your own; always follow the prescription and get your labs checked regularly.

If you miss a dose, take it as soon as you remember, unless it’s already close to your next dose. In that case, skip the missed one and keep your regular schedule. Doubling up can cause heart palpitations, anxiety, or tremors, which is why it’s safer to just miss one dose than to take two at once.

Common Side Effects and When to Call Your Doctor

Most people tolerate Synthroid well, but a few notice side effects, especially when the dose is too high. Look out for rapid heartbeat, shaky hands, insomnia, or feeling unusually warm. These signs usually mean your dose needs tweaking.

Allergic reactions are rare but serious. If you get a rash, itching, swelling, or trouble breathing, seek medical help right away.

Some medicines can interfere with Synthroid absorption. Calcium supplements, iron, antacids, and certain cholesterol drugs should be taken at least four hours apart. Always tell your pharmacist about every supplement and prescription you’re using.

Pregnant women often need a higher dose because their bodies produce more thyroid hormone. If you’re planning a pregnancy or discover you’re pregnant while on Synthroid, let your doctor know so they can adjust the dose and keep both you and the baby safe.

Remember, Synthroid isn’t a one‑size‑fits‑all solution. Your doctor will monitor your levels and adjust the dose as needed. If you ever feel off—like sudden weight loss, mood swings, or heart racing—call the clinic and ask for a blood test.On our site you’ll also find articles about other thyroid meds, safe supplement choices, and how to talk to your pharmacist about drug interactions. Use the search bar to explore topics like potassium supplements, safe online pharmacy purchases, and more.

Bottom line: Synthroid works best when you take it consistently, on an empty stomach, and keep up with regular blood work. Know the signs of too much or too little hormone, and never change the dose without a doctor’s OK. With the right routine, you can keep your thyroid in balance and feel like yourself again.