Medically reviewed on July 14, 2023 by Jordan Stachel, M.S., RDN, CPT. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.
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The thyroid is a gland that exists in the lower neck. It plays a key role in the body’s endocrine system, a messenger system wherein feedback loops release hormones that regulate energy levels, growth, and reproduction, among other processes. 
The thyroid, specifically, steadily releases various hormones to govern the metabolism and body’s development.2 However, fluctuations in these hormone levels can also impact other parts of the body, such as the reproductive system, which can cause menstrual irregularities. 
That said, the thyroid and the menstrual cycle are often interlinked, particularly in women or people assigned female at birth (AFAB) who’ve developed thyroid conditions during menopause, puberty, or pregnancy. 
First, It’s Important to Understand the Menstrual Cycle
The menstrual cycle occurs in the female reproductive system and consists of four distinct phases, each with its own unique characteristics and hormonal changes, including :
- Menstruation – The cycle begins with menstruation, the shedding of the uterine lining. It’s marked by the discharge of blood and tissue from the uterus through the vagina and typically lasts for three to seven days.
- Follicular Phase – The follicular phase starts on the first day of menstruation and ends with ovulation. During this phase, follicle-stimulating hormone (FSH) stimulates the ovaries to develop follicles, each containing an immature egg. These follicles produce estrogen, thickening the uterine lining in preparation for a pregnancy.
- Ovulation – Ovulation is crucial during the menstrual cycle. It occurs around the midpoint of the cycle, typically between day 12 and day 16. During ovulation, a mature egg is released from one of the ovaries and travels down the fallopian tube, ready for fertilization. This phase is triggered by a surge in luteinizing hormone (LH), which causes the follicle to rupture and release the egg.
- Luteal Phase – The luteal phase is next once ovulation is complete. During this phase, the ruptured follicle transforms into the corpus luteum, a temporary body that produces progesterone. Progesterone helps prepare the uterus for the possible implantation of a fertilized egg. If fertilization does not occur, the corpus luteum degenerates, leading to a decline in progesterone levels.
Next, It's Important to Understand Thyroid Hormones
The thyroid gland produces two hormones—thyroxine (T4) and triiodothyronine (T3)—that control your body’s metabolism and energy levels. These hormones are produced within the thyroid’s cells from iodine in the bloodstream. The thyroid gland also produces a third hormone called ‘calcitonin’, which is made by C-cells and supports bone growth. 
The pituitary gland helps ensure the thyroid produces the exact amount of hormones the body needs. Essentially, it acts as the thyroid’s boss, telling it to release more or less hormones. When T4 and T3 are released, they increase the body’s basal metabolic rate (BMR), or calories burned. 
In effect, the body will experience :
- Elevated body temperature
- Faster pulse
- Stronger heartbeat
- Physical and cognitive growth
- Improved concentration
- Improved reflexes
The Case of a Hormonal Imbalance
That said, hormone imbalances can occur. Because the pituitary gland also governs reproductive functioning, the thyroid and menstrual cycle are believed to be connected.  Due to the function of the pituitary gland and increased hormonal imbalance, there could also be a link between thyroid and fertility health.
More specifically, the pituitary gland triggers the release of gonadotropin-releasing hormone as well as the release of two more steroid hormones, which are :
- Luteinizing hormone (LH)
- Follicle-stimulating hormone (FSH)
In women and people AFAB, these hormones cause the ovaries to produce estrogen and progesterone, which regulate the uterus. 
Different Thyroid Conditions
Since the thyroid and female reproductive system are interconnected, thyroid dysfunction, such as hyperthyroidism and hypothyroidism, can influence menstruation and fertility. Most often, this type of dysfunction is a result of :
- Hormonal changes, such as during menopause, puberty, and pregnancy
- Dysfunctional gonadotropin release
- Changes in ovarian function
The effects of thyroid dysfunction on the menstrual cycle will depend on the type of prevalent thyroid issue, including:
- Hyperthyroidism – People with an overactive thyroid gland often experience hypomenorrhea, or abnormally low menstrual bleeding.
- Hypothyroidism – People with an underactive thyroid gland may experience oligomenorrhea and/or menorrhagia. Oligomenorrhea is characterized by irregular or inconsistent menstrual flow, while menorrhagia is menstrual bleeding that persists for over seven days. Those with menorrhagia may also experience heavy period bleeding. 
While thyroid function can affect the reproductive system, the opposite is also believed to be true. Steroid hormones, such as estrogen and progesterone, can impact thyroid hormones, particularly during pregnancy.  During gestation, the body also loses iodine, a key component of thyroid hormones, which can lead to hypothyroidism. 
All that said, thyroid disease—which includes both hyperthyroidism and hypothyroidism—impacts about one in eight women.  Besides contributing to menstrual irregularities, thyroid disease may also cause a period to stop for several months, a condition called "amenorrhea." If the ovaries are largely impacted, early menopause may also occur. 
Since thyroid disease impacts the whole process of the menstrual cycle, it can also affect ovulation. More specifically, hypothyroidism can prevent ovulation—the release of an egg from the ovary. In effect, this can negatively impact fertility. 
In addition to menstrual irregularities, overactive thyroid function may also cause :
- Mood changes, such as irritability, nervousness, or anxiety
- Trouble sleeping
- Weight loss
- An enlarged thyroid gland
- Muscle weakness
- Heat intolerance
- Vision problems
See related: Does Thyroid Medication Cause Weight Loss?
An underactive or low thyroid function, on the other hand, may lead to the following, in addition to heavy or frequent periods :
- Weight gain
- Dry hair
- Hoarse voice
- Cold intolerance
Who Does Thyroid Disease Affect?
Thyroid disease is fairly common; however, women and people AFAB are five to eight times more likely to develop the condition. Imbalances in thyroid hormone can impact all ages, and some people can even be born with hypothyroidism. 
People who are at a higher risk of thyroid disease most often :
- Have a family history of thyroid disease
- Have a medical condition, such as type 1 diabetes, lupus, or rheumatoid arthritis
- Take a high-iodine medication
- Are older than 60
- Have a history of a thyroid condition
What Causes Thyroid Disease?
The cause of thyroid disease depends on the type of thyroid dysfunction present. For example, hyperthyroidism is most often the result of :
- Graves’ disease
- Nodules on the thyroid
- Excessive iodine intake
Conversely, hypothyroidism may be caused by :
- Hashimoto’s thyroiditis
- Postpartum thyroiditis
- Iodine deficiency
- A non-functioning thyroid gland, such as from birth
How to Treat Thyroid Dysfunction
Accurate diagnosis is the first step in how to balance thyroid hormones and treat thyroid dysfunction. As noted, symptoms such as fatigue, weight changes, hair loss, and menstrual irregularities may indicate an underlying thyroid issue.
Healthcare providers typically perform blood tests to measure thyroid hormone levels, including thyroid-stimulating hormone (TSH), T3, and T4. Based on the results, they can determine the type and severity of thyroid dysfunction.
Once thyroid disease is diagnosed, common treatment plans include:
- Medication and/or hormonal treatment therapy – Hypothyroidism is commonly treated with a synthetic thyroid hormone replacement medication, such as levothyroxine. This medication helps restore normal hormone levels in the body, promoting overall well-being and regulating the menstrual cycle. Additionally, hormonal replacement therapy can address the imbalances caused by thyroid dysfunction, supporting the menstrual cycle's regularity and reducing associated symptoms. Hyperthyroidism is most often treated with antithyroid medications, such as propylthiouracil and methimazole, as well as radioactive iodine treatment or surgical removal of the thyroid.  (See related: [Does Thyroid Medication Affect the Menstrual Cycle?](https://www.everlywell.com/blog/thyroid/does-thyroid-medication-affect-menstrual-cycle/))
- Lifestyle modifications – Complementary to medical treatment, certain lifestyle changes can aid in managing thyroid dysfunction and can improve menstrual health. Eating a balanced diet rich in essential nutrients such as iodine, selenium, and zinc, is crucial for proper thyroid function. Regular exercise can also enhance metabolism and hormone regulation, potentially benefiting the menstrual cycle. Stress management techniques, including mindfulness, meditation, and adequate sleep, are also essential for maintaining hormonal balance. 
- Natural remedies – Some individuals may explore natural remedies and supplements to support thyroid function and improve the menstrual cycle. Certain herbs such as ashwagandha, guggul, bugleweed, gypsywort, gromwell, lemon balm, sage, and rosemary have shown promise in supporting thyroid health.  However, it’s important to consult a healthcare provider before starting any supplements, as they can interact with medications or have unintended side effects. 
- Regular monitoring – Monitoring thyroid hormone levels is crucial to ensure optimal treatment effectiveness. Healthcare professionals may periodically adjust medication dosages based on the person’s response and hormone levels. This ongoing evaluation helps maintain hormonal balance and supports a healthier menstrual cycle.
Treating thyroid dysfunction and its subsequent impact on the menstrual cycle is best achieved through a collaborative approach between an individual and healthcare provider. Individuals should communicate openly with their healthcare providers, share their symptoms and concerns, and adhere to their treatment plans for optimal results.
Additionally, regular check-ups, discussions about medication adjustments, and follow-up appointments will all contribute to effective thyroid dysfunction management and improved menstrual health.
Monitor Your Thyroid Health...Period.
Thyroid dysfunction, whether overactive or underactive, can impact the menstrual cycle. More specifically, a hyperactive thyroid may reduce menstrual bleeding, while an underactive thyroid may lead to a heavier and longer flow.
If you’re looking to monitor your thyroid hormone levels, Everlywell offers an easy-to-use, at-home Thyroid Test that can provide all the information you need. Begin by collecting a blood sample, then ship it to one of our certified labs, where your TSH, T3, and T4 levels will be tested.
Or, consult with a clinician using our online thyroid services. Through this telehealth program, we’ll connect you with a licensed provider who can meet with you virtually to discuss your concerns and recommend treatment.
Start your journey toward improved thyroid and menstrual health with Everlywell.
Does Thyroid Medication Affect the Menstrual Cycle?
What Is Thyroid Postpartum?
Can a Woman With Thyroid Problems Get Pregnant?
- John Hopkins Medicine . Anatomy of the Endocrine System. Johns Hopkins Medicine. Published 2019. URL. Accessed June 12, 2023.
- NCBI. How Does the Thyroid Gland work? Nih.gov. Published April 19, 2018. /URL. Accessed June 12, 2023.
- Jacobson MH, Howards PP, Darrow LA, et al. Thyroid hormones and menstrual cycle function in a longitudinal cohort of premenopausal women. Paediatric and Perinatal Epidemiology. 2018;32(3):225-234. URL. Accessed June 12, 2023.
- Cleveland clinic. Menstrual Cycle (Normal Menstruation): Overview & Phases. Cleveland Clinic. Published December 9, 2022. URL. Accessed June 12, 2023.
- National Cancer Institute. NCI Dictionary of Cancer Terms. National Cancer Institute. Published 2020. URL. Accessed June 12, 2023.
- Adlersberg MA, Burrow GN. Focus on Primary Care Thyroid Function and Dysfunction in Women. Obstetrical & Gynecological Survey. 2002;57(Supplement):S1-S7. URL. Accessed June 12, 2023.
- Orsu P, Koyyada A. Role of hypothyroidism and associated pathways in pregnancy and infertility: Clinical insights. Tzu Chi Medical Journal. 2020;32(4):312. URL. Accessed June 12, 2023.
- Thyroid disease | Office on Women’s Health. www.womenshealth.gov. URL. Accessed June 12, 2023.
- Cleveland Clinic. Thyroid Disease: Hypothyroidism & Hyperthyroidism | Cleveland Clinic. Cleveland Clinic. Published April 19, 2020. URL. Accessed June 12, 2023.
- Thyroid Medications. Johns Hopkins Lupus Center. URL. Accessed June 12, 2023.
- .Köhrle J. Selenium, Iodine and Iron–Essential Trace Elements for Thyroid Hormone Synthesis and Metabolism. International Journal of Molecular Sciences. 2023;24(4):3393. URL. Accessed June 12, 2023.
- Yarnell E, Abascal K. Botanical Medicine for Thyroid Regulation. Alternative and Complementary Therapies. 2006;12(3):107-112. URL. Accessed June 12, 2023.
- Kamal HI, Patel K, Brdak A, Heffernan J, Ahmad N. Ashwagandha as a Unique Cause of Thyrotoxicosis Presenting With Supraventricular Tachycardia. Cureus. 2022;14(3). URL. Accessed June 12, 2023.