Key Research Findings

The use of antithyroid drugs (ATDs) thiamazole (MMI) and propylthiouracil (PTU) is associated with a high frequency of side effects. 1 . When patients experience side effects with one (the 1st) ATD, it is usually discontinued and another is administered (the 2nd ATD). 1 . We investigated side effects associated with the 1st and 2nd ATDs. 1 .

The beneficial effects of anti-oestrogen therapy with tamoxifen and letrozole in the prevention of BC recurrence are well documented. 2 . While the most common side-effects of this therapy are well-defined, less is known about its effects on thyroid function. 2 . In women treated for early BC, an average of 1-5 kg weight gain has been observed after treatment with chemotherapy/anti-oestrogens. 2 . We aim to evaluate the current knowledge on the side effects of tamoxifen and letrozole treatments on thyroid function, followed by its potential influence on the observed weight gain. 2 .

Hypothyroidism is a common endocrine disease in the world that causes morbidity and mortality due to its association with metabolic diseases, especially in old age, and longterm treatment with levothyroxine causes many side effects for patients. 3 . Treatment with herbal medicine can regulate thyroid hormones and prevent side effects. 3 .

Reasons for Side Effects

Various medications, such as antithyroid drugs, anti-estrogen drugs, and hypothyroidism treatments, can cause side effects. Side effects may depend on how the drug works in the body or on an individual's susceptibility. For example, antithyroid drugs can cause hypothyroidism by inhibiting thyroid hormone production. 1 . Tamoxifen and letrozole may also affect thyroid function because they act on estrogen receptors. 2 . Levothyroxine is used to supplement thyroid hormone, but long-term use can lead to various side effects. 3 .

Common Side Effects

Hepatotoxicity

Antithyroid drugs can cause hepatotoxicity. 1 .

Cutaneous Reactions

Antithyroid drugs can cause cutaneous reactions. 1 .

Weight Gain

An average of 1-5 kg weight gain has been observed after treatment with chemotherapy/anti-oestrogens in women treated for early BC. 2 .

Thyroid Function Changes

Anti-oestrogen therapy with tamoxifen and letrozole can affect thyroid function. 2 .

Metabolic Diseases

Hypothyroidism can lead to increased morbidity and mortality due to its association with metabolic diseases, especially in old age. 3 .

Side Effect Management

Hepatotoxicity Management

It is important to have liver function tests done as directed by your doctor if there is a risk of hepatotoxicity. 1 .

Cutaneous Reaction Management

If you experience any skin reactions, consult your doctor. 1 .

Weight Gain Management

Maintaining a healthy diet and exercise is important to prevent weight gain. 2 .

Thyroid Function Changes Management

Regular thyroid function tests are crucial to prevent changes in thyroid function. 2 .

Metabolic Disease Management

Maintaining a healthy lifestyle is important to reduce the risk of metabolic diseases. 3 . Herbal therapy may help regulate thyroid hormones and prevent side effects. 3 .

Comparison Between Studies

Commonalities in Studies

All of these studies investigate the effects of medications on the body. 1 2 3 .

Differences in Studies

These studies differ in the medications investigated, research methods, and study populations. 1 2 3 .

Considerations for Real-Life Applications

The findings of these studies should be interpreted and applied appropriately by healthcare professionals. 1 2 3 .

Limitations of Current Research

These studies have limitations. 1 2 3 .

Future Research Directions

Further research is necessary to further investigate the findings of these studies. 1 2 3 .

Conclusion

Medications such as antithyroid drugs, anti-estrogen drugs, and hypothyroidism treatments can cause side effects. 1 2 3 . It is important to understand the risks and benefits of taking medications. 1 2 3 . If you have any questions or concerns, consult your doctor. 1 2 3 .