Hashimoto's and Constipation: Can an Underactive Thyroid Cause It?

Maybe you've noticed that your bowel movements have changed recently.

You're going to the toilet less often, your stools have become harder, or it takes more effort to empty your bowels.

Sometimes you also experience bloating, abdominal discomfort, or that frustrating feeling that you haven't completely finished after using the bathroom.

If you have Hashimoto's, you may wonder: **could this constipation be caused by my underactive thyroid?**

It could. Constipation is a recognized symptom of hypothyroidism, or an underactive thyroid.

But not everyone with Hashimoto's has hypothyroidism. And constipation can have other causes too.

That's why it's important to look beyond your thyroid and consider what else might be affecting your digestion.

What Is Constipation?

Constipation doesn't simply mean that you don't have a bowel movement every day.

How often someone goes to the toilet varies from person to person.

For some people, daily bowel movements are normal. Others may go only a few times a week without experiencing any problems.

With constipation, you might notice that:

- You have bowel movements less often than usual.
- Your stools are hard or dry.
- You need to strain.
- Passing stool is painful or difficult.
- You feel as though your bowels haven't emptied completely.
- Your abdomen regularly feels full or bloated.

So it's not only about how often you go to the bathroom, but also about changes in your usual pattern and the symptoms that come with them.

Why Can an Underactive Thyroid Cause Constipation?

Thyroid hormones play an important role in many processes throughout your body.

Your stomach and intestines are affected by them too.

When your thyroid doesn't produce enough hormone, certain processes can slow down. This includes the movement of food and stool through your digestive tract.

When stool stays in the large intestine for longer, more water may be absorbed from it.

As a result, stools can become harder and drier, making bowel movements more difficult.

This is one reason constipation can occur with hypothyroidism.

Is Constipation Caused by Hashimoto's or Hypothyroidism?

This distinction matters.

Hashimoto's is an autoimmune condition in which the immune system attacks the thyroid gland.

Over time, this may reduce the thyroid's ability to produce hormones. When the body doesn't have enough thyroid hormone, hypothyroidism develops.

Constipation is primarily associated with this reduced thyroid function.

You can therefore have Hashimoto's while your TSH and free T4 levels remain within the reference range and your thyroid still produces enough hormone.

If you experience constipation in that situation, Hashimoto's itself isn't necessarily the cause.

What Other Symptoms Can Occur With an Underactive Thyroid?

When constipation is related to hypothyroidism, you may experience other symptoms too.

Perhaps you're constantly tired, feel cold more easily, or notice that your skin has become drier.

Hair loss, concentration difficulties, muscle symptoms, weight gain, or changes in your menstrual cycle can also occur.

You don't need to experience all these symptoms.

And constipation combined with fatigue doesn't automatically mean you have hypothyroidism.

Blood tests are needed to assess thyroid function.

How Do You Know if Your Thyroid Is Underactive?

If your healthcare professional suspects hypothyroidism, thyroid function can be assessed with blood tests.

These usually include TSH and free T4.

With primary hypothyroidism, TSH is usually elevated. When TSH is high and free T4 is low, this generally indicates overt hypothyroidism.

If TSH is elevated while free T4 remains within the reference range, subclinical hypothyroidism may be present.

Changes in bowel movements may therefore be a reason to discuss your symptoms, but constipation alone can't tell you how well your thyroid is functioning.

Why Am I Constipated Even Though My Thyroid Levels Are Normal?

Perhaps you take levothyroxine and your thyroid levels are considered appropriate, but bowel movements are still difficult.

That can be frustrating.

However, it doesn't automatically mean you need more thyroid medication.

Constipation has many possible causes.

These include insufficient fiber, inadequate fluid intake, limited physical activity, changes in eating habits, and certain medications or supplements.

Pregnancy, changes in your daily routine, irritable bowel syndrome, and other digestive conditions may also play a role.

Sometimes several factors contribute at the same time.

If your thyroid levels are appropriate and symptoms continue, it's worth looking into other possibilities.

Can Medications and Supplements Cause Constipation?

Yes. Some medications can slow bowel movements.

Examples include certain strong painkillers and some antidepressants.

Iron and calcium supplements can also cause constipation in some people.

Perhaps your symptoms began after starting a new medication or adding a supplement.

Discuss this with your healthcare professional or pharmacist, and don't stop prescribed medication on your own.

If you take levothyroxine, there's something else to keep in mind.

Iron and calcium can reduce levothyroxine absorption when taken too close together.

Follow the recommended timing between your thyroid medication and these supplements.

Can Fiber Help With Constipation?

Fiber can help support regular bowel movements.

You'll find it in vegetables, fruit, whole grains, legumes, nuts, and seeds.

Eating too little fiber may contribute to constipation.

But you don't need to suddenly add huge amounts of fiber to your diet.

In fact, increasing fiber too quickly can cause extra gas and bloating.

Build up gradually and make sure you're drinking enough fluids.

Does Drinking More Water Help With Constipation?

Adequate fluid intake is important for normal bowel movements.

If you're not drinking enough, this may contribute to hard stools.

But that doesn't mean drinking more and more water will automatically solve constipation.

If you're already adequately hydrated, large amounts of extra water may not improve your symptoms.

Consider the bigger picture, including diet, fluids, activity, and other possible causes.

Can Exercise Help Get Your Bowels Moving?

Regular physical activity may help support bowel function.

It doesn't need to be an intense workout.

Walking, cycling, or another form of movement that suits you can be part of a healthy daily routine.

If you're experiencing significant fatigue with Hashimoto's or hypothyroidism, you don't need to force yourself through a difficult workout to get your bowels moving.

Choose activities that suit your energy, fitness, and overall health.

Do You Need to Have a Bowel Movement Every Day?

No. There's no rule that everyone must have a bowel movement daily.

Normal bowel habits vary.

Perhaps you've had a bowel movement every other day for years without any discomfort.

That doesn't necessarily indicate a problem.

But if you usually go daily and suddenly only have bowel movements twice a week, with hard stools and significant straining, that's a noticeable change.

The difference from your usual pattern is especially important.

Can Constipation Also Cause Bloating?

Yes, it can.

When stool remains in your intestines longer, you may experience fullness or bloating.

Gas can also contribute.

Perhaps your abdomen feels increasingly tight as the day goes on, or your clothes feel tighter.

But bloating has other possible causes too.

So feeling bloated doesn't automatically mean your constipation is caused by your thyroid.

Will Constipation Improve With Levothyroxine?

If constipation is genuinely related to thyroid hormone deficiency, treatment with levothyroxine may help.

However, don't expect your bowel movements to return to normal immediately after your first tablet.

Your body needs time to adjust to treatment, and thyroid hormone levels change gradually.

If constipation continues despite appropriately treated thyroid function, other causes may be involved.

**Never increase your levothyroxine dose on your own to improve bowel movements.**

How often you use the bathroom doesn't determine how much thyroid medication you need.

What Can You Try at Home for Constipation?

For mild constipation, simple habits may help.

For example:

- Drink enough fluids throughout the day.
- Regularly eat fiber-rich foods.
- Increase fiber gradually.
- Include some physical activity in your day.
- Go to the bathroom when you feel the urge.
- Take your time on the toilet.
- Avoid prolonged, excessive straining.
- Consider whether medications or supplements may be contributing.

Some people find a regular toilet routine helpful, such as after breakfast.

But don't force yourself to have a bowel movement at a particular time every day.

The goal is a bowel pattern that's normal and comfortable for you.

When Can Laxatives Help?

Sometimes changes to diet, fluid intake, and physical activity aren't enough.

In those situations, laxatives may be an option.

Different types work in different ways.

Which one is suitable depends on your symptoms, health, and any other medications you're taking.

A healthcare professional or pharmacist can help you choose an appropriate option, especially if constipation is persistent or keeps returning.

Don't use Hashimoto's as a reason to combine more and more digestive remedies or supplements on your own.

Is It Useful to Track Your Bowel Movements?

It can be helpful when you're trying to understand why your bowel habits have changed.

You don't need to keep a detailed diary every day.

A short record may be enough.

For example, note how often you have bowel movements, whether stools are hard or soft, and whether you need to strain.

You can also record when symptoms began, which medications or supplements you use, and whether you have other new symptoms.

This may help you recognize patterns and explain changes more clearly during a medical appointment.

The goal isn't a perfect daily bowel movement. It's understanding your own usual pattern.

When Should You See a Doctor About Constipation?

Contact your healthcare professional if constipation persists, keeps returning, or becomes progressively worse.

A clear, unexplained change in your usual bowel habits is also worth discussing.

Seek medical assessment sooner if you experience blood in your stool, unexplained weight loss, fever, persistent vomiting, or severe abdominal pain.

Severe abdominal pain, a markedly swollen abdomen, repeated vomiting, or being unable to pass both stool and gas may require urgent medical assessment.

Don't wait because you assume it's only your underactive thyroid.

What Should You Remember?

Constipation is a recognized symptom of hypothyroidism.

And because Hashimoto's is a common cause of an underactive thyroid, the two can be connected.

But constipation doesn't automatically mean Hashimoto's is getting worse.

Bowel movements are affected by many different factors, including diet, fluids, physical activity, medications, and your overall health.

**Look at the bigger picture rather than focusing only on your thyroid.**

If symptoms continue, appropriate medical evaluation can help identify the cause and find a suitable approach.