Medically reviewed on Sept 20, 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.
Table of contents
Depending on the function of your thyroid, signs your thyroid medication is working will differ. When treating an underactive thyroid, or hypothyroidism, the medication your healthcare provider prescribes will increase the production of the thyroid hormone. After taking the medication regularly, you should start to feel more energetic and you may also start to lose weight. 
Conversely, taking hyperthyroidism medication, which treats a thyroid gland that produces too much of the thyroid hormone, will regulate hormone production and ease symptoms of an overactive thyroid, such as fatigue, hair loss, and heat intolerance. 
Within the endocrine system exists numerous glands that control hormone production throughout the body. The thyroid is one such gland that’s located at the base of the neck and regulates your metabolism and development. 
The pituitary gland, located at the base of the brain, is considered the “master” of the endocrine system. It produces a critical thyroid hormone, called thyroid stimulating hormone (TSH). In turn, TSH stimulates the thyroid gland, causing the secretion of two key thyroid hormones :
T3 is the active form of thyroid hormone, and T4 is converted into T3. If the conversion is ineffective, it’s likely that you’ll develop some form of hypothyroidism, which affects 5 in 100 Americans. 
This can occur when you lack certain components in your diet, such as if a person eats very few fruits and vegetables and/or they consume more processed carbohydrates and sugars. Additional causes of hypothyroidism include :
People with an underactive thyroid can experience symptoms such as :
Hyperthyroidism is less common, impacting 1 in 100 Americans. Graves’ disease, thyroid nodules, inflammation, iodine, and noncancerous tumors can each trigger the production of surplus thyroid hormones. While symptoms will vary from person to person, hyperthyroidism typically manifests as :
Additionally, taking too much of a hypothyroidism medication can shift thyroid hormone production in the opposite direction, and it may actually cause hyperthyroidism. Because of this, it’s critical to monitor your thyroid function and check your hormone levels regularly when taking any form of thyroid medication. 
To treat hypothyroidism, healthcare providers will prescribe a drug called levothyroxine (Eltroxin®). It’s a synthetic T4 hormone replacement that supplements thyroid hormones to help regulate your :
While levothyroxine starts to work immediately, a few weeks will pass before your symptoms show signs of improvement. From there, you can gauge the thyroid hormone medication’s effectiveness by monitoring the following 5 signs :
Once you’ve been prescribed levothyroxine, your healthcare provider will likely set up an appointment to conduct a blood test, beginning six weeks following your start date. These tests will measure thyroid hormones to assess the effectiveness of the medication. 
That said, levothyroxine is a lifelong treatment, and you’ll need to visit your healthcare provider about once a year to monitor your hormone levels. Pregnant women will have to go more frequently, typically once a month. 
If the medication is ineffective, your healthcare provider may then seek another diagnosis since hypothyroidism symptoms can imitate other diseases and disorders, such as:
See related: PCOS and Hypothyroidism
When prescribed hormone replacement pills, fatigue and feelings of depression should begin to disappear.  Consider making daily journal entries to gauge your mood and energy levels as you continue treatment for your thyroid condition.
If your tiredness does not subside, ensure you’re taking your medication consistently and consider taking the medication on an empty stomach, barring any gastrointestinal side effects. Further, avoid taking your medication at the same time as daily vitamins high in iron or calcium, as this can inhibit the absorption of the thyroid hormone replacement. 
Women with hypothyroidism often present with irregular menstrual cycles. In some cases, they may experience heavy periods. In other cases, periods may be infrequent or entirely absent. When ovulation doesn’t occur, women may have trouble with fertility. Accordingly, it’s essential that women wanting to become pregnant receive treatment. 
Levothyroxine replenishes the thyroid hormone. It returns the body to homeostasis and may regulate your menstrual cycle so that you experience more regular ovulation and periods. If you aren’t experiencing positive effects, speak to your healthcare provider about increasing your dosage.
Dry, thick, and coarse skin and hair are common side effects of hypothyroidism. Your nails can also become brittle and you may experience mild facial swelling. 
While you may experience hair loss within the first month of taking levothyroxine, the medication will rebalance your hormone levels, and your hair growth should resume to normal once your hormones stabilize. 
Weight gain is commonly associated with hypothyroidism since your metabolic rate decreases. However, it’s typically not a severe increase—only five to 10 pounds of weight gain on average. This type of weight gain is often a combination of water and salt. 
That said, levothyroxine is still effective in helping those with an underactive thyroid maintain a healthy weight, helping people lose around 10% of their body weight. 
See related: Heterogeneous Thyroid
There are several types of treatment for an overactive thyroid. A type of highly effective radiotherapy, called radioactive iodine treatment, targets the thyroid gland and destroys cells to limit the production of thyroid hormones. Patients only require a single treatment, but it will take a few weeks or months before you experience the full effect. That said, this isn’t a safe treatment method for people who are pregnant or breastfeeding. 
Some healthcare providers may recommend removing the thyroid completely or partially through surgery if the thyroid is swollen or if you’re experiencing eye problems as a result of the disorder. But, some people wonder, “can you live without a thyroid?” Yes, you can. If the thyroid is completely removed, your healthcare provider will prescribe levothyroxine in turn.
Alternatively, there are medications available for hyperthyroidism treatment. These anti-thyroid drugs include :
When taken, these drugs block the thyroid from making hormones. A healthcare provider may also prescribe beta blockers to manage the symptoms of hyperthyroidism, such as :
That said, beta blockers are often paired with another form of treatment that targets the thyroid directly. 
Generally, when taking medication for hyperthyroidism, your blood hormone levels will normalize, helping to improve your symptoms. More specifically, signs that your hyperthyroidism medication is working include:
One of the most noticeable signs that your hyperthyroidism medication is working is a stabilization of your body weight. 
Hyperthyroidism often leads to unintentional weight loss due to an increased metabolism. As the thyroid medication begins to regulate your thyroid hormone levels, you may find that your weight starts to stabilize and gradually return to a healthier range. 
Hyperthyroidism can take a toll on your emotional well-being, causing mood swings, anxiety, and irritability. 
When the thyroid medication successfully controls excessive thyroid hormone production, you may experience improved mood stability. Anxiety and emotional turbulence may subside, and you may feel more emotionally balanced and at ease.
Excessive thyroid hormone levels can also lead to feelings of restlessness and hyperactivity. 
Effective hyperthyroidism medication can help rein in these symptoms and restore your energy levels to a more normal state. You'll likely notice a reduction in the constant feeling of being on edge and may experience improved overall energy and vitality.
Hyperthyroidism can cause your heart rate to become dangerously elevated, leading to palpitations and an increased risk of heart-related complications. 
When your thyroid hormone medication starts to work, you'll likely notice that your heart rate becomes more stable and falls within a healthy range.
Muscle weakness and fatigue are common symptoms of hyperthyroidism. 
As the medication effectively controls thyroid hormone levels, you may regain strength and notice improved muscle stability. Everyday tasks that were once challenging may become easier, and you may also find it easier to engage in physical activities or exercise.
While the symptoms of your thyroid disorder should ease once you begin thyroid medication, blood tests are the best way to measure the effectiveness of your treatment plan. If symptoms don’t subside, this may be one of many signs that your thyroid medication is too low.
Make an appointment with your healthcare provider or order an At-Home Thyroid Test from Everlywell. With a simple finger prick, you can collect a blood sample from the comfort of your own home and send it to our partnered third-party CLIA-certified labs. Then, you’ll receive clinically validated tests with your results and recommended next steps, including prescriptions.
The test itself measures TSH, T3, and T4 thyroid hormones, as well as thyroid antibodies. Prioritize your health today by discovering what Everlywell can do for you.