8 Signs Your Thyroid Medication Is Working

How to know if your thyroid medication is working

Thyroid medications can help relieve your symptoms and get your hormone levels into the normal range. After you start taking thyroid hormone medication, it may take a few weeks for your levels to improve. 

In the meantime, here are eight signs to help you know that your thyroid medication is working.

1. Normal hormone levels

One of the goals of thyroid hormone therapy is to get your hormone levels into the normal range (being in this range is called “euthyroid”). To determine your levels, a healthcare professional may do a thyroid panel, which is a blood test. This includes a test to check your level of thyroid stimulating hormone (TSH) and other thyroid indicators like T3 and T4. 

After your initial full thyroid panel, a healthcare professional may just monitor your TSH level to see if any medication changes are necessary. Once a normal TSH level is reached, you’ll continue to take the same dose of thyroid medication unless you start to have symptoms.

If your levels remain within your target range, you may only have your TSH checked once or twice a year. 

2. Weight stabilization

Thyroid hormone is critical for normal metabolism. And weight gain is one of the first symptoms people notice when their thyroid levels are low. People who have an underactive thyroid may gain 5 lbs to 10 lbs before being diagnosed with hypothyroidism. 

With treatment, your weight should stabilize. You may lose some of the gained weight as your metabolism becomes more active.

3. Improved energy levels

Thyroid hormone helps control the production of energy in the body. When thyroid levels are low, your cells can’t maintain energy levels to get you through the day. That’s why people with hypothyroidism feel tired or fatigued. 

If your thyroid medication is working, you should notice improved energy levels and less fatigue. Most people notice improvement in fatigue within a few weeks of being on the right dose of thyroid medication.

4. Feeling less cold

People with hypothyroidism tend to feel cold. If you have hypothyroidism, your body’s thermostat isn’t able to generate heat when the room temperature drops. 

One study found that people produced more heat when their thyroid levels were normal. You may notice that you feel less cold as your thyroid medication starts to work. 

5. Improved mood

Although experts don’t know exactly why, hypothyroidism is strongly linked to low mood and depression. Thyroid replacement hormone frequently improves mood in those with low thyroid hormone levels. And some people with depression and normal thyroid levels see better results when thyroid hormone is used with antidepressants.

6. More regular menstrual cycles

The thyroid gland and its hormones are critical for normal menstrual cycles, sexual development, and fertility. If thyroid hormones are too high or too low, it can disrupt menstrual cycles and even cause them to stop altogether (amenorrhea). Once normal thyroid hormone levels are reached, menstrual cycles usually normalize. 

7. Skin and hair changes

Many people report dry skin and hair loss as one of the first symptoms when their thyroid hormone is low.

With low thyroid hormone levels, hair and skin cells divide more slowly. This can cause hair to fall out and wounds to take longer to heal. Skin cells also make less moisturizing secretions. Fortunately, dry skin and hair loss improve with normal thyroid levels. 

8. Less constipation

Constipation, stool that’s hard to pass, or needing to strain to have a bowel movement sometimes happens with hypothyroidism. Experts think that low thyroid hormone may slow all body processes, even how fast the bowels move. 

They’re not exactly sure how it happens. But the good news is that bowel movements usually improve when you reach normal thyroid hormone levels.

How long does it take for thyroid medicine to work?

Thyroid medication starts working right away. But it may take 4 to 6 weeks to notice improvement in your symptoms. Some people start feeling better sooner. 

Don’t stop taking your thyroid medication because you’re not seeing immediate results. Make sure you keep your follow-up appointments and get the necessary blood tests. This will help your team adjust your dose in a timely manner.

Medications for hypothyroidism

The goal of medications for hypothyroidism is to get thyroid hormone levels in the normal range. 

Thyroid hormone can be replaced in two ways: 

• T3 is the active form of thyroid hormone — it has three iodine molecules. 

• T4 has four iodine molecules and gets converted to active T3 by cells throughout the body.

There are three types of medication used to treat hypothyroidism:

• Levothyroxine (Synthroid, Levoxyl, Tirosint): Levothyroxine contains synthetic T4.

• Liothyronine (Cytomel): Liothyronine contains synthetic T3.

• Desiccated thyroid (Armour Thyroid): Desiccated thyroid contains both T3 and T4 from animal sources.

Signs your thyroid medication is too low

The signs that your thyroid medication dose is too low are the same as when you have hypothyroidism. Basically, every system in your body slows down. And if you miss several doses of thyroid medication, you can have the same symptoms. 

Some of the signs that your thyroid medication is too low are:

• Fatigue

• Hair loss, dry skin

• Constipation

• Cold intolerance

• Depression

• Difficulty concentrating

• Slower heart rate

• Irregular menstrual cycles

• Weight gain

Your healthcare team will check your thyroid levels after starting you on medication. They’ll adjust your dose based on your symptoms and thyroid tests.

Signs your thyroid medication is too high

The signs that your thyroid medication dose is too high are the same as if you had hyperthyroidism (an overactive thyroid). Some of the signs of a high thyroid medication dose include:

• Anxiety or nervousness

• Racing heart

• Diarrhea

• Excessive sweating

• Weight loss

• Heat intolerance

Let your healthcare team know right away if you have any of these symptoms while taking thyroid medication. They’ll check your thyroid levels and adjust your medication dosage if needed.

Why is your thyroid medication not working like it should?

Getting your thyroid medication dose right is just one step in making sure it works like it should. 

Here are some of the common reasons you might not be seeing the results you expect:

• You switched between Synthroid and generic levothyroxine. If a healthcare professional prescribed brand-name Synthroid, it’s best not to switch to a generic. If you started with generic levothyroxine, you’ll want to stick with the same generic and the same manufacturer.

• Your weight has changed quite a bit. As with most medications, if you’ve gained or lost weight, you may need to adjust the dose of your thyroid medication. 

• You took your thyroid medication with food. You must take Synthroid and levothyroxine on an empty stomach.

• You took your thyroid medication with vitamin supplements. Iron and calcium supplements can interfere with how your body absorbs thyroid medications. And biotin can interfere with a thyroid blood test. Stop taking biotin at least 2 days before doing a TSH blood test. 

• You took your thyroid medication with your stomach medications. Omeprazole (Prilosec), esomeprazole (Nexium), and pantoprazole (Protonix) can interfere with how well thyroid medication works. If you’re taking treatment for stomach acid, a healthcare professional may need to increase the dosage of your thyroid medication.

• You started estrogen hormone therapy or birth control. Any form of estrogen can affect your thyroid medication and how it’s absorbed.

• You eat a lot of fiber. Many foods and high-fiber fruits and vegetables can interfere with its absorption. Thyroid hormone is best absorbed in a fasted state, in the morning, or 4 hours after your last meal.

Can any food or supplement help your thyroid medication work better?

Foods or supplements will not make your thyroid medication work better. In fact, they may keep the gut from fully absorbing your medication. That’s why it’s best to do both of the following:

• Take your thyroid medication by itself. 

• Have a waiting period of at least 60 minutes before you eat or take any supplements. 

Avoid eating these foods or taking these supplements right after your thyroid medication: 

• Walnuts

• High-fiber foods (like broccoli, beans, or pumpkin)

• Iron

• Calcium

• Antacids

When should you take your thyroid medication?

You should take your thyroid medication at the same time each day — preferably in the morning. To avoid any food interaction, it’s best to take it about 1 hour before breakfast. That’s because your levothyroxine is most effective on an empty stomach. 

For some, it can be difficult to time this dose in the morning. If nighttime dosing is more convenient for this reason, that’s OK, too. The best time to take your thyroid medication is any time you can do it consistently.

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Written by:

Frank Schwalbe, MD

Frank Schwalbe, MD, is an assistant professor of anesthesiology at the Yale School of Medicine. He has practiced anesthesiology for 30 years.

Edited by:

Patricia Pinto-Garcia, MD, MPH

Patricia Pinto-Garcia, MD, MPH, is a medical editor at GoodRx. She is a licensed, board-certified pediatrician with more than a decade of experience in academic medicine.

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