Thyroid Problems: Underactive vs Overactive Signs and Treatment
The thyroid is a small gland in the neck that controls how fast your body uses energy, and when it is underactive or overactive it can affect weight, energy, mood, heart rate and more. Thyroid problems are common, especially in women, and a simple blood test can diagnose them.
What Does the Thyroid Do?
The thyroid makes hormones that set your metabolism, which affects body temperature, heart rate, digestion, energy and mood. When it makes too little or too much hormone, many body systems are affected, and symptoms can be easy to mistake for stress, ageing or other conditions.
Underactive vs Overactive Thyroid
- Tiredness and sluggishness
- Weight gain
- Feeling cold
- Constipation and dry skin
- Hair thinning and low mood
- Weight loss despite eating normally
- Fast or irregular heartbeat
- Sweating and feeling hot
- Anxiety, shaking hands and trouble sleeping
- Frequent bowel movements
Learn more about one common symptom in why hypothyroidism causes fatigue. Hair changes are also common; see hair fall: common causes and what can help.
Common Causes
How Is It Diagnosed and Treated?
Your doctor will check your symptoms and order blood tests, mainly TSH and thyroid hormones. An underactive thyroid is usually treated with a daily thyroid hormone tablet. An overactive thyroid may be treated with anti-thyroid medicines, radioactive iodine or surgery. Always take thyroid medicine exactly as prescribed, keep your follow-up blood tests and ask your pharmacist about interactions, because some supplements such as calcium and iron can affect absorption. Never stop or change a dose without medical advice.
- You have a very fast heartbeat, chest pain or trouble breathing
- You have a high fever, confusion or severe weakness
- You feel extremely cold, drowsy and confused
Have questions about your thyroid medicine?
Talk to a pharmacist before changing how you take any medicine.
Contact usFrequently Asked Questions
Can thyroid problems cause weight gain?
An underactive thyroid can cause modest weight gain, but it rarely explains large weight changes on its own.
Is a thyroid problem hereditary?
Autoimmune thyroid disease often runs in families.
Can diet fix my thyroid?
Diet cannot replace treatment, but a balanced diet supports overall health.
More Reading
Sources: American Thyroid Association (ATA) patient information; NHS guidance on underactive and overactive thyroid; National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK) on thyroid disease.