Common Signs of an Underactive Thyroid You Shouldn’t Ignore

The thyroid is a small, butterfly-shaped gland located at the base of your neck — but don’t let its size fool you. This tiny gland plays a massive role in regulating metabolism, energy levels, body temperature, and even mood. When it slows down and doesn’t produce enough hormones, the condition is known as hypothyroidism, or an underactive thyroid. If left untreated, it can lead to serious health complications.

Recognizing the early warning signs of a sluggish thyroid can help you take action before symptoms worsen.

1. Unexplained Fatigue

One of the most common and easily overlooked symptoms of an underactive thyroid is ongoing fatigue. If you’re getting enough rest but still feel sluggish, it could be because your thyroid isn’t producing enough hormones to keep your body’s systems running at full speed.

2. Weight Gain

People with hypothyroidism often experience weight gain despite not changing their diet or exercise routine. A slower metabolism caused by low thyroid hormone levels means your body burns fewer calories — even at rest.

3. Cold Sensitivity

Do you feel cold when others are comfortable? The thyroid helps regulate your body temperature. When it’s underactive, you may find yourself reaching for a sweater even on mild days.

4. Dry Skin and Thinning Hair

A lack of thyroid hormones can slow skin cell turnover, resulting in dry, flaky skin. It can also weaken hair follicles, leading to thinning hair or even hair loss, particularly on the scalp and eyebrows.

5. Depression or Mood Changes

The thyroid affects brain chemistry, including the production of serotonin — the “feel good” hormone. An underactive thyroid can lead to low mood, irritability, or even depression.

6. Slow Heart Rate and Constipation

A slower metabolism impacts many body functions, including heart rate and digestion. People with hypothyroidism often have a low pulse and may experience frequent constipation.

7. Memory Problems or Brain Fog

Forgetfulness or difficulty concentrating — commonly referred to as "brain fog" — is another lesser-known symptom of an underactive thyroid. These cognitive issues may improve with proper treatment.

When to Get a Thyroid Test

If you’re experiencing any of these symptoms, especially in combination, it’s important to talk to your healthcare provider and ask for a thyroid test. A simple blood test measuring levels of TSH (thyroid-stimulating hormone) and other thyroid hormones can confirm whether your thyroid is underactive.

The Link to Other Conditions

An underactive thyroid can also influence or be influenced by other conditions such as high cholesterol, depression, and prediabetes. In fact, some patients seeking prediabetes treatment discover that poor thyroid function is contributing to their blood sugar issues.

Final Thoughts

Recognizing the common signs of an underactive thyroid is the first step toward feeling better. With early diagnosis and appropriate treatment — typically in the form of daily hormone replacement medication — most people can manage their symptoms effectively. Don’t ignore the signs; take control of your health by scheduling a thyroid test today.