Your thyroid—a small gland in your neck—has a huge impact on your body. It produces thyroid hormone (TH), which is responsible for keeping your metabolism, heartbeat, temperature, mood, and more, in check. An underactive thyroid doesn't produce enough TH, and that can cause a host of health problems. Watch the video for the warning signs.

RELATED: 19 Signs Your Thyroid Isn't Working Right

Don't have time to watch? Read the full transcript:

You're exhausted: Too little thyroid hormone makes you feel fatigued.

You've gained weight: An underactive thyroid slows your metabolism.

Your skin is dry and itchy: Hair and nails might be brittle, too.

You're feeling down: Thyroid hormones can affect brain chemistry and mood.

You've got brain fog: A sluggish thyroid can make you forgetful and fuzzy-headed.

You're all backed up: Digestion slows down, making you constipated.

Your flow is like whoa: Say hello to longer, heavier periods with more cramps.

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You're constantly cold: Total system slowdown = less energy burned. That means less body heat.

Think you have a thyroid problem? See your doc and ask to get tested.