Can taking liothyronine sodium 25 mcg tablets cause weight gain? [Step-by-step Guide 2026]

Liothyronine sodium 25 mcg tablet is a prescription thyroid hormone medicine containing synthetic triiodothyronine (T3). It may be prescribed for certain people with hypothyroidism when additional thyroid hormone replacement is considered appropriate. Because thyroid hormones influence metabolism and energy use, many people wonder whether taking liothyronine can cause changes in body weight.

So, can taking liothyronine sodium 25 mcg tablet cause weight gain? In most cases, weight gain is not considered a typical effect of taking the correct dose of liothyronine. In fact, excessive thyroid hormone replacement can produce symptoms associated with an overactive thyroid, including increased appetite and weight loss. However, changes in body weight can happen for several reasons, and the underlying thyroid condition, treatment response, diet, activity level, and other medicines may all play a role.

What Is Liothyronine Sodium 25 mcg?

Liothyronine is a synthetic form of triiodothyronine (T3), one of the hormones naturally produced by the thyroid gland. Thyroid hormones help regulate how the body uses energy and support the normal function of organs and tissues.

A 25 mcg tablet is one available strength of liothyronine. The appropriate dose varies from person to person and depends on factors such as the thyroid condition being treated, other medicines, age, and individual response.

Importantly, liothyronine should be taken only as prescribed. The official prescribing information specifically warns that thyroid hormones should not be used for obesity or weight loss, because taking excessive amounts can cause serious or potentially life-threatening complications.

Does Liothyronine Cause Weight Gain?

Generally, weight gain is not a typical direct effect of properly dosed liothyronine.

If a person has hypothyroidism, the condition itself can contribute to weight gain because an underactive thyroid can reduce energy expenditure. The American Thyroid Association explains that some weight gain associated with hypothyroidism is related to salt and water retention, and treatment can help return body weight toward the person’s previous baseline.

This means that someone who starts thyroid hormone treatment might notice changes in weight over time, but that does not necessarily mean the medicine itself is causing weight gain.

The situation becomes different if thyroid hormone levels are not adequately controlled. Too little thyroid hormone may allow hypothyroid symptoms to continue, while too much can cause symptoms of excessive thyroid hormone activity.

The American Thyroid Association notes that too little thyroid medicine may leave symptoms such as tiredness, feeling cold, and constipation, while too much can cause nervousness, a fast heartbeat, feeling hot, or weight loss.

Why Might Someone Gain Weight While Taking Liothyronine?

If you notice weight gain while taking liothyronine sodium 25 mcg tablet, several factors may need to be considered.

1. The underlying thyroid condition

Hypothyroidism itself can contribute to weight gain. If thyroid hormone levels remain below the desired range, symptoms associated with an underactive thyroid may continue.

2. Weight changes after thyroid levels normalize

When hypothyroidism is treated, the body may move back toward its normal weight. This can sometimes be perceived as unexpected weight fluctuation, particularly if thyroid function was abnormal for a significant period.

3. Diet and physical activity

Body weight is influenced by calorie intake, physical activity, sleep, lifestyle, and many other factors. Thyroid treatment does not make a person completely resistant to ordinary factors that influence weight.

4. Other medicines or health conditions

Certain medicines and medical conditions can contribute to weight changes. If weight gain continues despite appropriate thyroid treatment, your healthcare professional may want to consider other possible causes.

5. Thyroid levels may need monitoring

Thyroid hormone therapy requires appropriate dosing and monitoring. The American Thyroid Association recommends checking thyroid function after starting or changing thyroid hormone treatment, commonly around 6–8 weeks, depending on the clinical situation.

Can Liothyronine Help With Weight Loss?

Liothyronine should not be used as a weight-loss medicine.

Although thyroid hormones affect metabolism, taking additional thyroid hormone when it is not medically necessary does not provide a safe method for losing weight. The official prescribing information carries a boxed warning stating that thyroid hormones, including liothyronine sodium, should not be used to treat obesity or promote weight loss. Excessive doses can cause serious toxicity.

Liothyronine treatment should therefore focus on treating an appropriate thyroid-related medical condition rather than producing a specific number on the weighing scale.

What Should You Do If You Gain Weight?

If you experience unexplained or significant weight gain after starting liothyronine sodium 25 mcg tablet, do not increase, decrease, or stop your dose on your own.

Instead, speak with your doctor or pharmacist. They may review your symptoms, medication schedule, other medicines or supplements, and thyroid blood tests to determine whether your treatment needs adjustment.

The American Thyroid Association advises patients to contact their healthcare professional if they experience substantial weight gain or loss, or if thyroid-related symptoms return or become worse.

Also seek prompt medical attention if you develop concerning symptoms such as chest pain, a very rapid or irregular heartbeat, severe shortness of breath, or other serious symptoms.

FAQs

1. Can taking liothyronine sodium 25 mcg tablet cause weight gain?

Weight gain is not generally considered a typical effect of correctly dosed liothyronine. If weight gain occurs, the underlying thyroid condition, thyroid hormone levels, lifestyle factors, other medicines, or another health condition may be involved.

2. Does liothyronine 25 mcg help you lose weight?

Liothyronine is not approved as a weight-loss treatment. Using thyroid hormones specifically for weight reduction can be dangerous, particularly at doses above normal hormone requirements.

3. Why am I gaining weight even though I take thyroid medicine?

Weight can be influenced by many factors. Persistent hypothyroid symptoms, inadequate treatment, diet, activity level, sleep, other medicines, and unrelated health conditions may all contribute.

4. Should I increase my liothyronine dose if I gain weight?

No. Do not change your liothyronine dose without medical advice. Too much thyroid hormone can cause excessive thyroid activity and potentially serious complications.

5. How long does it take for thyroid treatment to affect weight?

The response varies between individuals and depends on how severe the thyroid problem was before treatment. Weight should not be used as the only measure of whether thyroid treatment is working. Your healthcare professional can assess symptoms and thyroid blood tests together.

6. Is 25 mcg of liothyronine a high dose?

Whether 25 mcg is appropriate depends on the individual and the reason for treatment. The correct dose should be determined by a qualified healthcare professional based on your thyroid status, medical history, and response to treatment.

Final Thoughts

So, can taking liothyronine sodium 25 mcg tablet cause weight gain? Usually, weight gain is not considered a direct or expected effect of properly dosed liothyronine. More often, weight changes in people with thyroid disease are connected to the underlying thyroid condition, changes in thyroid hormone levels, lifestyle factors, or other health issues.

Liothyronine is a potent thyroid hormone and should be used carefully under medical supervision. It should never be taken or adjusted specifically for weight loss. If you experience unexpected weight changes while taking it, discussing the change with your healthcare professional is the safest approach.

Medical disclaimer: This article is intended for general educational and SEO purposes and does not replace professional medical advice, diagnosis, or treatment. Always take liothyronine exactly as prescribed and consult your healthcare professional before changing your medication or dosage.