Hypothyroidism can be dangerous if left untreated, though it is generally manageable with proper treatment.
Untreated hypothyroidism can lead to serious complications, including heart disease, high cholesterol, nerve damage (peripheral neuropathy), fertility issues, and mental health problems like depression and memory issues.
In rare cases, myxedema coma—a life-threatening condition caused by severe, long-term untreated hypothyroidism—can occur. This requires immediate emergency medical treatment and can be fatal even with treatment.
Myxedema coma is more common in older adults and can be triggered by stressors like infection, cold exposure, or sedatives.
However, when properly treated with thyroid hormone replacement (like levothyroxine), people with hypothyroidism typically have a normal life expectancy and can live healthy lives.
Early diagnosis and consistent treatment are key to preventing serious health risks.
human disease
Factsheet
Hypothyroidism Molecular structure of thyroxine, which is deficient in hypothyroidism
Pronunciation /ˌhaɪpəˈθaɪrɔɪdɪzəm, -poʊ-/
Specialty Endocrinology
Hypothyroidism Molecular structure of thyroxine, which is deficient in hypothyroidism
Pronunciation /ˌhaɪpəˈθaɪrɔɪdɪzəm, -poʊ-/
Specialty Endocrinology
MedlinePlus
medlineplus.gov › home › health topics
Hypothyroidism | Hashimoto's Disease | MedlinePlus
Hypothyroidism can contribute to high cholesterol. In rare cases, untreated hypothyroidism can cause myxedema coma. This is a condition in which your body's functions slow down to the point that it becomes life-threatening.
Mayo Clinic
mayoclinic.org › diseases-conditions › hypothyroidism › symptoms-causes › syc-20350284
Hypothyroidism (underactive thyroid) - Symptoms and causes - Mayo Clinic
December 10, 2022 - Understand what happens when your thyroid is underactive and learn about treatment for this condition.
Videos
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Hypothyroidism | Clinical Medicine - YouTube
How is hypothyroidism diagnosed?
Hypothyroidism is diagnosed through a blood test called thyroid-stimulating hormone (TSH). A high TSH level indicates low thyroid hormone levels. If you have high TSH levels on a blood test, your healthcare team will order more tests to confirm the diagnosis and to look for its cause.
goodrx.com
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What Happens If You Leave Hypothyroidism Untreated? - GoodRx
What are some common signs of hypothyroidism?
Hypothyroidism symptoms can be subtle and can be mistaken for stress, aging, or lifestyle factors. Common signs include: Low energy Unexplained weight gain Dry skin Hair loss Brittle nails Irregular periods Other symptoms may involve: Feeling cold Forgetfulness Tingling sensations Swelling Cramps Constipation Decreased libido If you notice these changes, listen to your body and discuss them with a healthcare professional.
goodrx.com
goodrx.com › goodrx health › health conditions › hypothyroidism: symptoms, causes, and treatments › what happens if you leave hypothyroidism untreated?
What Happens If You Leave Hypothyroidism Untreated? - GoodRx
What is the life expectancy of a person with hypothyroidism?
When treated properly, people with hypothyroidism have a normal life expectancy. Untreated or poorly managed hypothyroidism may increase the risk of heart disease and other health issues, though, which can reduce your lifespan. Regular monitoring of your thyroid hormone levels can help make sure you avoid any serious complications.
goodrx.com
goodrx.com › goodrx health › health conditions › hypothyroidism: symptoms, causes, and treatments › what happens if you leave hypothyroidism untreated?
What Happens If You Leave Hypothyroidism Untreated? - GoodRx
NHS
nhs.uk › conditions › underactive-thyroid-hypothyroidism
Underactive thyroid (hypothyroidism) - NHS
An underactive thyroid (hypothyroidism) is a common condition where the thyroid gland in your neck does not make enough hormones. This can cause symptoms like tiredness and weight gain.
GoodRx
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What Happens If You Leave Hypothyroidism Untreated? - GoodRx
By clicking a topic in the ... may receive compensation in relation to your search. Untreated hypothyroidism can lead to serious mental and physical health problems....
Published May 22, 2025
NIDDK
niddk.nih.gov › home › health information › endocrine diseases › hypothyroidism (underactive thyroid)
Hypothyroidism (Underactive Thyroid) - NIDDK
October 3, 2025 - Some babies are born with a thyroid that is not fully developed or does not work properly. If untreated, congenital hypothyroidism can lead to intellectual disability and growth failure—when a baby doesn’t grow as expected. Early treatment can prevent these problems.
Associated Endocrinologists
endocrinemds.com › home › blogs › blog › thyroid disease is a life-threatening disease
Thyroid Disease is a Life-threatening Disease - Associated Endocrinologist, P.C.
March 11, 2024 - If this happens, thyroid disease can worsen progressively, ultimately leading to life-threatening complications. Both hyperthyroidism and hypothyroidism can be deadly if left untreated. Some of the most dangerous thyroid disease complications ...
Children's Hospital of Philadelphia
chop.edu › conditions-diseases › hypothyroidism
Hypothyroidism in Children | Children's Hospital of Philadelphia
Hypothyroidism is a common endocrine disorder in which your child’s thyroid gland does not produce enough thyroid hormone. A child with an underactive thyroid may experience fatigue, weight gain, constipation, decreased growth, and a host of other issues. What is hypothyroidism?Hypothyroidism ...
Penn Medicine
pennmedicine.org › home › conditions we treat › hypothyroidism
Hypothyroidism – Symptoms and Causes | Penn Medicine
1 month ago - Managing hypothyroidism is something you’ll need to do for the rest of your life, and we’re here to support you with advanced treatments, regular follow-up visits, and expert care. Hypothyroidism doesn’t have to slow you down.
Cleveland Clinic
my.clevelandclinic.org › health › diseases › 8541-thyroid-disease
Thyroid Disease: What It Is, Causes, Symptoms & Treatment
June 2, 2025 - This is the process of how your body transforms the food you consume into energy. All the cells in your body need energy to function. When your thyroid isn’t working properly, it can impact your entire body. The two main types of thyroid disease are hypothyroidism (underactive thyroid) and hyperthyroidism (overactive thyroid).
Johns Hopkins Medicine
hopkinsmedicine.org › health › conditions-and-diseases › hypothyroidism
Hypothyroidism | Johns Hopkins Medicine
The goal of treatment is to return your levels of thyroid hormone back to normal. Untreated hypothyroidism may lead to anemia, low body temperature, and heart failure.
Mayo Clinic
mayoclinic.org › diseases-conditions › hashimotos-disease › symptoms-causes › syc-20351855
Hashimoto's disease-Hashimoto's disease - Symptoms & causes - Mayo Clinic
April 30, 2025 - Heart problems. Hypothyroidism can result in poor heart function, an enlarged heart and irregular heartbeats. It can also result in high levels of low-density lipoprotein (LDL) cholesterol — the "bad" cholesterol — that is a risk factor ...
Medical News Today
medicalnewstoday.com › articles › 324535
Symptoms of Hypothyroidism (underactive thyroid)
May 2, 2025 - Without treatment, this heart condition may result in serious complications, such as high or low blood pressure or heart failure. Untreated hormone disorders, including thyroid problems, can contribute to hair loss.
American Thyroid Association
thyroid.org › home › hypothyroidism
Hypothyroidism | American Thyroid Association
September 10, 2015 - From Clinical Thyroidology® for the Public: Hypothyroidism is quite common, most often as a result…
Mount Sinai
mountsinai.org › health-library › diseases-conditions › hypothyroidism
Hypothyroidism Information | Mount Sinai - New York
It's important to remember that treating hypothyroidism does not cure the problem, it only controls it. And once you're on Thyroid hormone replacement, you're probably on it for life. The good news is that once your thyroid situation is properly regulated, you'll probably feel a whole lot better.
American Academy of Family Physicians
aafp.org › pubs › afp › issues › 2021 › 0515 › p605.html
Hypothyroidism: Diagnosis and Treatment | AAFP
May 15, 2021 - Clinical hypothyroidism affects one in 300 people in the United States, with a higher prevalence among female and older patients. Symptoms range from minimal to life-threatening (myxedema coma); more common symptoms include cold intolerance, ...
Better Health Channel
betterhealth.vic.gov.au › health › conditionsandtreatments › thyroid-hypothyroidism
Thyroid - hypothyroidism | Better Health Channel
Hypothyroidism can be either primary or secondary. Primary hypothyroidism means that the thyroid gland itself is diseased, while secondary hypothyroidism is caused by problems with the pituitary gland, the brain structure that supervises the thyroid gland.
British Thyroid Foundation
btf-thyroid.org › hypothyroidism-leaflet
Hypothyroidism
Read about symptoms of an underactive thyroid (hypothyroidism) and how this thyroid disorder is diagnosed and managed
Healthy WA
healthywa.wa.gov.au › Articles › F_I › Hypothyroidism-underactive-thyroid
Hypothyroidism (underactive thyroid)
Hypothyroidism is a lifelong condition where your thyroid gland doesn’t make enough thyroid hormones.
Everyday Health
everydayhealth.com › health conditions › thyroid disease › hypothyroidism
What Happens if Hypothyroidism Is Left Untreated?
November 19, 2023 - Because your thyroid affects so many areas of your body, untreated hypothyroidism can cause widespread harm. Here are complications to watch out for. A goiter is an enlarged thyroid gland, and it happens when the organ is trying extra hard to ...
MD Anderson Cancer Center
mdanderson.org › cancerwise › 2023 › 10 › signs of thyroid issues: how do you know if you have them?
Signs of thyroid issues: How do you know if you have them? | MD Anderson Cancer Center
It normally starts with “hyper” symptoms, then gradually goes to the other extreme. It’s very common and in the majority of cases, gets better on its own without hormone replacement. Still, some patients may need to follow up to make sure they haven’t developed hypothyroidism.