Key takeaways
- Levothyroxine is a synthetic hormone that replaces thyroxine (T4) and converts it into T3, the active form of the hormone, helping to regulate your metabolism when taken correctly.
- To make sure the medication is absorbed effectively, take levothyroxine on an empty stomach with water, waiting 30 to 60 minutes before eating or taking supplements, especially those containing calcium or iron.
- It typically takes 4 to 6 weeks to experience the full effects of levothyroxine, and regular monitoring by a healthcare team is crucial to adjust the dosage and maintain optimal thyroid hormone levels.
Overview
Your thyroid plays an essential role in your metabolism. The butterfly-shaped gland at the base of your neck makes hormones that affect your heart, muscles, and digestive function. It even regulates your body temperature.
When your thyroid doesn’t make enough of these hormones, you might receive a hypothyroidism diagnosis. Symptoms of hypothyroidism can include feeling cold, constipation, fatigue, weight gain, and dry skin and hair. It can also lead to mental health conditions, heart conditions, and fertility difficulties.
Levothyroxine is a medication that is used to manage hypothyroidism. There are different things you can expect when you start taking this drug.
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About levothyroxine
Levothyroxine (Levoxyl) is the first-line treatment for diagnosed hypothyroidism. This synthetic hormone is designed to work just like the natural thyroid hormone your body produces. It’s chemically identical, but it’s made in a lab.
The medication gives your body more of the hormone thyroxine (T4). When taken in proper doses, it will help return your thyroid hormone to optimal levels. It’s usually taken orally, but it also comes as an injectable form.
Treatment with levothyroxine is usually lifelong. If you stop taking the medication, your symptoms will return.
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Get free cardWhat to expect when starting levothyroxine
Understanding what happens in the body after you take levothyroxine can help you manage your condition successfully.
Day 1
Once the medication enters your bloodstream, the T4 hormone is converted into T3 (triiodothyronine). This is the active form of the hormone that gets to work in your body.
There are a lot of factors that can affect how levothyroxine is absorbed, so doctors often give instructions on how to take it.
You should take it on an empty stomach first thing in the morning, with a full glass of water. Then wait 30 to 60 minutes before eating or drinking anything else, including coffee. Otherwise, your body won’t receive most of the thyroid hormone from the medication.
What’s more, calcium and iron can bind to levothyroxine and carry it from the body before it’s able to do any work. This is the case whether the minerals are in food or from a supplement. Therefore, aim to take supplements or foods — like yoghurt or milk — containing iron and calcium at least 4 hours after levothyroxine.
Antacids that contain calcium carbonate, aluminum, or magnesium can also affect absorption.
In weeks 1 to 3
In the first week of treatment, your thyroid levels will begin to rise, which will help your metabolism to work as it should.
Other changes can include more stable blood sugar, improved body temperature regulation, and a less sluggish digestive system.
However, as these changes are gradual, it’s unlikely you’ll notice a difference within the first few weeks of treatment.
If you notice rapid improvement within 1 week, your dose may be too high. Taking too much levothyroxine can cause the thyroid to become overactive (hyperthyroidism), and this comes with a new set of symptoms.
In weeks 4 to 6
You can expect peak effects to hit after 4 to 6 weeks. This means you’ll likely notice changes in your symptoms if you were experiencing symptoms of hypothyroidism.
Generally, the 4- to 6-week mark is when a doctor or healthcare professional will want to repeat bloodwork to check thyroid levels. Your dosing may need an adjustment to get it right.
A healthcare professional will monitor you until your thyroid hormones reach optimal levels. Be sure to keep them updated on changes to your morning routine, like giving up coffee or adding yogurt to breakfast, as they may need to adjust your dosage accordingly.
Signs your thyroid medication is working
The key sign that your thyroid medication is working is that your thyroid hormones reach an acceptable level. The only way to know this for sure is by getting a blood test from a healthcare professional.
However, there are other signs that your medication is working that you can look out for. These include:
- Weight management: Weight gain may be a symptom of an underactive thyroid. When your medication is working, you may find it easier to lose the weight you had gained, if you want to.
- Feeling more energetic: Your thyroid can help with energy production. When your medication is working, you might notice feeling more energetic.
- Reduced symptoms: If you were experiencing symptoms previously, a key sign that levothyroxine is working is that you may notice your symptoms easing.
What side effects can you expect with levothyroxine?
Here are the most common side effects you may notice when you take levothyroxine:
- irregular heartbeats
- shortness of breath
- muscle cramps, pain, or weakness
- increased appetite
- feeling hot
- feeling depressed or irritable
- diarrhea
Summary
Levothyroxine is a prescription medication that healthcare professionals prescribe for an underactive thyroid.
You should notice the effects after around 4–6 weeks, as anything sooner can mean your dosage is too high.
Working with a healthcare team is important, and letting them know about any changes to your morning routine, including what you are having for breakfast, can help them monitor your dosage best.
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