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Hyperthyroidism: Signs and Symptoms of an Overactive Thyroid

min read

By Jeff Hayward

Medically Reviewed by Dr. Gerald Morris

Having a key part of your endocrine system work too hard can actually be detrimental to your health. We’re referring specifically to the thyroid gland, which is the butterfly-shaped gland in the midline of your neck that plays a big role in your body’s metabolism.

There are different reasons why your thyroid may be overproducing hormones, including Graves’ disease (which is an autoimmune disorder). If you suspect it may be acting up, here are eight signs of an overactive thyroid to be on the lookout for.


The NHS in the UK explains that one big sign of hyperthyroidism is having nervous energy, which may seem more pronounced if you’re not usually an anxious person. The source says that “nervousness, anxiety and irritability” can be signs your thyroid gland is working overtime. Tremors can also be a sign.

You may also be hyperactive, meaning you can’t sit still, which will likely be associated with the nervous energy, adds the source. If your body and mind are constantly racing and you don’t know why, then ask your doctor to check your thyroid (among other things).


On the flipside of the coin, you may also be experiencing listlessness and exhaustion from hyperthyroidism, notes You’d think an overproduction of hormones would make you constantly active like in the last point, but that’s not always the case.

One of the reasons you might be exhausted from hyperthyroidism is that you’re having difficulty sleeping. “Difficulty sleeping can also be due to the stress on your body from having a rapid pulse, higher blood pressure, diarrhea, tremors, anxiety, and other symptoms of hyperthyroidism,” adds the source.

Increased Appetite

Having a huge appetite out of nowhere may be tied to your thyroid function, explains the Mayo Clinic. It explains that hyperthyroidism can actually boost the amount of food you take in, but at the same time, you may be suddenly (and unexplainably) losing weight.

Dropping pounds without any change in diet is not usually a good sign, but it may not be hyperthyroidism. Check with your doctor with regard to major changes in appetite and weight fluctuations.

Irregular Heartbeat

Too much thyroid hormone can set off abnormal heart rhythms (known clinically as arrhythmias), according to Harvard Medical School. One of the most common abnormalities is a faster resting heart rate (known medically as sinus tachycardia), says the source.

This condition can cause your heart rate to exceed 100 beats per minute (the average resting heart rate for adults is between 60 to 100). Another problem that can occur is atrial fibrillation (or AFib), which is when your heart’s upper chambers are out of synch with the lower chambers and often described as “quivering.”

High Blood Pressure

The Mayo Clinic explains that hyperthyroidism can lead to secondary high blood pressure (hypertension), which is when your blood pressure is high from another medical condition. While high blood pressure can be dangerous, like primary hypertension there are usually no symptoms, notes the clinic.

You may have high blood pressure from hyperthyroidism (or another medical condition) if it doesn’t respond to blood pressure medication (or current medications stop being effective), it’s very high (systolic blood pressure greater than 180-mmHg or diastolic blood pressure greater than 120-mmHg), and if there’s no family history of high blood pressure, says the source.


This refers to the physical enlargement of your thyroid gland, which can be tied to thyroid issues. “It is important to know that the presence of a goiter does not necessarily mean that the thyroid gland is malfunctioning,” explains the American Thyroid Association.

An overactive thyroid can swell, but so can a thyroid that’s underactive (hypothyroidism), adds the source. There could be another condition related to the enlargement of your thyroid, which should be examined by a medical professional.

Hair Loss/Brittle Hair

Brittle hair that breaks or falls out can also be tied to thyroid problems, says the DS Laboratories blog. “If you suffer from thyroid disorders, there is now enough scientific evidence to show that your thyroid impacts your hair,” it notes. This is because thyroid hormones control so many bodily functions, including healthy hair growth.

The source also explains that hair loss from thyroid issues “may only become apparent several months after the onset of the disease itself.” Aside from brittle hair, you may also experience an itchy, dry scalp from hyperthyroidism.

Intolerance to Heat says that the specific hormone thyroxine made by the thyroid can raise your metabolism, which leads to a rise in body temperature. This could lead you to feel warmer in a normal climate room or feel more heat stress outside on a hot day.

The source says a number of other factors can contribute to heat intolerance. So, if you know you have an overactive thyroid, perhaps cut back on caffeine, which can also speed up your metabolism. Blood pressure or allergy medications could also be the culprit.

MD, Family Medicine, Internal Medicine

Gerald Morris, MD is a family medicine/internal medicine physician with over 20 years expertise in the medical arena. Dr. Morris has spent time as a clinician, clinical research coordinator/manager, medical writer, and instructor. He is a proponent of patient education as a tool in the diagnosis and treatment of acute and chronic medical conditions.

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