Signs your thyroid medication is working

Thyroid disorders are often due to changes in the thyroid gland, a small butterfly-shaped gland at the base of the neck. The gland can sometimes produce too much T4 thyroid hormone (hyperthyroidism) or too little (hypothyroidism).

These two conditions often cause opposing symptoms. For example, hyperthyroidism can cause a quick metabolism, while hypothyroidism can cause weight gain.

Whether your thyroid is overproducing or underproducing, it can cause symptoms such as mood changes, weight changes, and fatigue.

Taking thyroid medication can help to relieve these symptoms. You can look for several signs to ensure your treatment is working. This includes:

Changes to thyroid hormone levels

Thyroid-stimulating hormone (TSH), produced by the pituitary gland, promotes the release of the thyroid hormones T4 and T3. When you don’t have enough thyroid hormones, you can experience high levels of TSH. When you have too much thyroid hormones, your TSH levels will be low.

During treatment for a thyroid disorder, you will undergo regular monitoring in the form of blood tests. These blood tests will allow a doctor to monitor your levels of TSH and T4.

A doctor typically will take a blood sample between 4 and 6 weeks after you start treatment. These tests will allow them to assess if the medication they prescribe is working. Medications aim to increase or decrease the amount of thyroid hormone in your bloodstream.

Monitoring blood tests can help to check that your levels are getting closer to typical levels, including:

• TSH at 0.5–5.0 mIU/L
• T4 levels at 0.7–1.9ng/dL
• T3 is rarely monitored as it can be unreliable

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Weight changes

Thyroid disorders can affect your metabolism and energy levels. As a result, people often experience weight change.

For example, hypothyroidism causes a slow metabolism, which you may recognize through weight gain and fatigue. On the other hand, hyperthyroidism causes a rapid metabolism, which leads to weight loss.

After you start receiving treatment for a thyroid condition, you will likely notice weight change as the treatment works to balance your thyroid activity.  

According to a study from 2020, after starting treatment for hyperthyroidism, people often notice weight gain due to their metabolism slowing down.

If you have any questions about avoiding weight changes when starting treatment for a thyroid disorder, consider speaking with a health professional, such as a dietician. They can offer dietary advice to help make the transition easier.

Changes to heart rate

As your treatment starts to work, your heart rate may slightly decrease or speed up depending on the condition you are receiving treatment for. This is because of the changes in your metabolism.

For example, if you have hyperthyroidism, your heart rate is likely to be slightly quick. Treatment will help to slow this down, whereas if you have hypothyroidism, it will help to increase your blood pressure.  

Mood changes

Treating thyroid disorders often helps to treat other mood disorders that occur as a symptom. For example, up to 40% of people with hypothyroidism go on to develop clinical depression.

Treatment for thyroid abnormalities can be effective in also getting rid of symptoms of depression. So, as the treatments start to work, your mood may improve at the same time.

However, for some mood symptoms of hyperthyroidism that include anxiety, additional treatments may be necessary.  

How long does it take to feel the effects of thyroid medication?

While thyroid medication will start to work straight away, it can take several weeks for you to notice any changes to your symptoms.

Common medications for hypothyroidism peak in effectiveness after 4–6 weeks of taking it. However, if you have hyperthyroidism, the average time treatment takes to get rid of your symptoms is 3 months.  

Types of thyroid medication

The medication a doctor will recommend will depend on the type of thyroid disorder you have.

If you have hyperthyroidism, some treatments a doctor may prescribe to you include:

• Radioactive iodine therapy (RAI): This involves you swallowing radioactive iodine either as a liquid or pill. It gathers in your thyroid gland, where it begins to destroy thyroid cells.

• Antithyroid medications: They compete against molecules that are important to produce thyroid hormones, reducing the levels of these hormones in your bloodstream. This includes medications such as methimazole (Northyx) and propylthiouracil (Propycil).

• Surgery: If your symptoms are severe or you are planning to conceive, a near-total or total thyroidectomy may be suggested.

Common treatment options for hypothyroidism include the medication levothyroxine (Levoxyl). It is available as a pill or liquid and works to replace thyroid hormones your body would otherwise normally produce.

It is often recommended that you take this before eating first thing in the morning.

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When to speak with a doctor

If you notice any of the following symptoms, you may wish to speak with a doctor about receiving a test for a thyroid disorder:

• fatigue
• unexplained weight changes
• irregular periods

Summary

Medications for thyroid disorders differ depending on the type of condition you have. Signs that treatments are working include the reversal of any noticeable symptoms, such as weight and mood changes.

There are a variety of treatments available to treat your condition. Working with a healthcare professional can help determine the best treatment path for you.

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