1. Sensitivity to Hot and Cold Temperatures
Your thyroid is a small but powerful gland that plays a major role in controlling your metabolism and regulating your body temperature. When it’s not functioning properly, your ability to tolerate different temperatures can change dramatically. Many people don’t realize that thyroid issues can make them unusually sensitive to heat or cold.

Feeling overheated or unable to handle warm environments is especially common in those with hyperthyroidism (an overactive thyroid), but temperature sensitivity can show up with almost any thyroid problem—even autoimmune conditions. Noticing that you get hot more easily than others can be an early sign that your thyroid is struggling.

On the opposite end, if you feel cold all the time or can’t seem to warm up, that may point to hypothyroidism, where the thyroid is underactive. Both conditions interfere with the body’s ability to regulate temperature properly.

If you’ve recently become more sensitive to hot or cold weather than usual, it’s worth paying attention. Temperature intolerance is often a subtle but important clue that something may be off with your thyroid.

2. Needing to Pee More Often Than Usual
Although the thyroid doesn’t directly control the bladder, thyroid hormone imbalances can still affect urinary function. Both hypothyroidism and hyperthyroidism can influence how the kidneys work, which may lead to more frequent urination.

In some cases, an overactive thyroid can speed up kidney function, causing you to urinate more often. With hypothyroidism, fluid balance can also be disrupted, contributing to bladder changes. These shifts may lead to symptoms similar to an overactive bladder (OAB), such as needing to pee more often than usual or feeling like you can’t hold it as long.

If you notice a new pattern of frequent urination—especially along with other thyroid-related symptoms—it may be worth having your thyroid levels checked.

3. Unexplained Weight Changes
Your thyroid plays a major role in controlling your metabolism—the rate at which your body burns calories. When thyroid hormones are out of balance, your weight can change in ways that don’t match your eating or activity levels.

With hypothyroidism, your metabolism slows down. This can lead to gradual, unexplained weight gain even if your diet and exercise routine haven’t changed. Many people find it difficult to lose weight until their thyroid levels are corrected.

With hyperthyroidism, the opposite happens. Your metabolism speeds up, causing unintentional weight loss. You may notice you’re losing weight despite eating normally—or even feeling hungrier than usual.

If your weight suddenly shifts without a clear explanation, your thyroid could be playing a role.

4. Changes in Heart Rate
Thyroid hormones directly affect your heart, so one of the earliest signs of a thyroid issue can be changes in your heart rate or rhythm.

In hyperthyroidism, your heart may beat faster than normal or feel like it’s racing. Some people experience palpitations—strong, noticeable heartbeats that can feel unsettling.

In hypothyroidism, your heart rate may slow down. This can leave you feeling tired, weak, or lightheaded.

Because heart symptoms can overlap with many other conditions, it’s important not to ignore them—especially if they appear alongside other thyroid-related warning signs.

5. Changes in Skin, Hair, and Nails
Your thyroid helps regulate cell growth, which includes the cells in your hair, skin, and nails. When thyroid levels are out of balance, these tissues can show visible signs of trouble.

With hypothyroidism, the skin often becomes dry, rough, or flaky. Hair may thin out, shed more easily, or feel coarse. Nails can become brittle and break more often.

With hyperthyroidism, some people experience increased hair shedding or fine, thin hair, along with warm or overly moist skin.

These changes usually develop gradually, so they’re easy to overlook. But together, they can signal a deeper hormonal imbalance.

6. Mood or Cognitive Changes
Your thyroid doesn’t just affect your body—it affects your brain. Shifts in thyroid hormone levels can change your mood, energy, and mental clarity.

Hypothyroidism often slows everything down. You may feel more tired, sad, forgetful, or mentally foggy. Concentration becomes harder, and tasks may feel more overwhelming than usual.

Hyperthyroidism, on the other hand, often speeds the brain up. Some people feel anxious, restless, irritable, or unusually emotional. Sleep can become difficult, which only worsens the symptoms.

Because these emotional and cognitive changes can be mistaken for stress, burnout, or anxiety disorders, the thyroid is often overlooked. But identifying the hormonal cause can make a major difference.