On This Page – Quick Medical Summary
What myxedema coma is, and who needs to act fast
Myxedema coma is a rare, life-threatening emergency that can develop when severe hypothyroidism goes untreated. NIDDK’s overview of hypothyroidism describes it as a state where the body’s functions slow to a dangerous point, which needs immediate treatment.
Is it really a coma?
Usually not. Most people are confused or drowsy rather than unconscious, which is why some clinicians call it a myxedema crisis.
When to call 911 right now
- Seeing these symptoms right now: call 911 and bring their medication list.
- Worried about a lab number, not symptoms: see which TSH levels need urgent care.
- A loved one is already hospitalized: the outcomes and treatment sections below explain what comes next.
ℹ️ Medical Disclaimer: This article is general education about myxedema coma. It does not replace emergency care, diagnosis, treatment decisions, medication changes, or hospital procedures. If you suspect myxedema coma, call 911. For ongoing thyroid care, consult a board-certified endocrinologist before starting, stopping, or changing any thyroid medication.
Myxedema coma symptoms: the red flags to know
Myxedema coma symptoms reflect body systems that have slowed to a dangerous point. The most recognized warning signs are:
- Confusion, extreme drowsiness, or unresponsiveness
- Low body temperature
- Slow heart rate
- Low blood pressure
- Slow or shallow breathing
- Puffy, non-pitting swelling of the skin
📊 Clinical Data Point: In a 2025 systematic review of 698 cases, 88.9% of people with confirmed myxedema coma had altered mental status. — Source: Myxedema coma: challenges and future directions, a systematic survey and review, 2025 (PubMed)
Emergency signs
Any mix of these signs in someone with hypothyroidism needs emergency care. Earlier signs of an underactive thyroid, like fatigue and feeling cold, often come first.
Why older adults get missed
In older adults, the signs can mimic infection or stroke, which delays the diagnosis.
⚠️ Clinical Warning: Don’t wait for confusion or sleepiness to clear on its own. Myxedema coma needs immediate hospital care.
How untreated low thyroid tips into a crisis
In long-standing hypothyroidism, the body adapts to low thyroid hormone until a new stress, such as infection, overwhelms those adaptations.
🔬 How It Works: Thyroid hormone helps regulate temperature, heart function, breathing, and thinking. After years of deficiency the body copes by slowing down, and a new illness can tip several systems into failure.
Common triggers
Infection is the most common trigger. Others include heart attack, stroke, and surgery, as well as sedatives, antipsychotics, and cold exposure. Stopping thyroid medication is another.
Who is most at risk
Hypothyroidism is more common in women and people over 60. In Japan’s national inpatient database, patients with myxedema coma averaged 77 years old and two-thirds were women. The NIH-hosted StatPearls clinical review notes it can be the first sign of undiagnosed hypothyroidism.
How rare and how deadly is myxedema coma?
Myxedema coma is rare, and published death rates range from about 20% to as high as 60%. A 2025 systematic review of 698 cases found an overall mortality of 38.8%.
These figures describe hospitalized people who were often already seriously ill from a trigger like infection. They are not a prediction for any one person.
What the numbers show
| Source | Patients | Key Finding | Key Clinical Detail |
|---|---|---|---|
| 2025 systematic review | 698 cases | 38.8% died | Shock and multiorgan failure led causes of death |
| Japan inpatient database, 2010–2013 | 149 patients | 29.5% in-hospital deaths | About 1.08 cases per million per year |
| US National Inpatient Sample, 2016–2018 | 2,495 hospitalizations | 7% vs 0.7% without myxedema coma | Stay about 9 days vs 4 |
Sources: PubMed-indexed studies; US figures via the American Thyroid Association’s public summary of the study.
Why published death rates differ
Reviews pool published case reports. An analysis of US hospital records instead relies on hospital diagnosis codes, so the figures aren’t directly comparable.
How doctors diagnose it, and where your TSH fits
Myxedema coma is diagnosed mainly at the bedside, from symptoms combined with blood tests.
Why treatment can start before results
Because delays are dangerous, treatment is recommended on clinical suspicion rather than after lab results. No single agreed set of diagnostic criteria exists.
🔬 How It Works: One published scoring system adds points across six areas. They are a triggering event, body temperature, brain function, digestive findings, heart function, and metabolic results like sodium.
When TSH can mislead
A chart of what your TSH result means helps with everyday monitoring. In a crisis, though, thyroid hormone levels don’t reliably reflect severity. Rare case reports also describe myxedema coma with a normal TSH.
✅ Patient Action: Ask your endocrinologist: “Is my hypothyroidism from the thyroid gland or the pituitary, and is TSH the right test for me?”
How myxedema coma is treated in the hospital
Treatment happens in an intensive care unit, and it starts quickly.
Thyroid hormone and steroids
The core treatment is thyroid hormone given through a vein (IV levothyroxine) plus hydrocortisone, a steroid. The steroid is typically continued until doctors rule out a coexisting adrenal problem.
🩺 Editor’s Note: Published expert reviews note the best thyroid hormone dose and form are still debated. Too much can strain the heart and too little may not reverse the crisis, so dosing stays with the ICU team.
Supportive ICU care
Care also supports breathing, blood pressure, and temperature, and treats the trigger, such as infection. Some patients need a breathing machine.
✅ Patient Action: Ask the ICU team: “Is endocrinology involved, and what is the thyroid medication plan at discharge?”
Preventing a thyroid crisis: what families can do
Myxedema coma can affect people whose hypothyroidism is undiagnosed, undertreated, or unmedicated because they ran out of pills.
Don’t stop thyroid medicine without advice
Running out of or stopping thyroid medication is a documented trigger. If doses are being missed, our guide to how levothyroxine is absorbed and what interferes with it can help.
Tell every clinician about hypothyroidism
Before surgery or a new sedative, make sure every clinician knows about the thyroid condition. Watch older relatives closely in winter, when cases cluster.
✅ Patient Action: Ask your endocrinologist: “What should we do with thyroid medicine if they’re sick or can’t take pills?”
Myxedema coma FAQs
1. What triggers myxedema coma?
Infection is the most common myxedema coma trigger; others include surgery, heart attack, stroke, sedatives, cold exposure, and stopping thyroid medication.
2. Who is most at risk of myxedema coma?
Older adults with long-standing hypothyroidism face the highest myxedema coma risk, and women are affected more often than men.
3. Can you survive myxedema coma?
Yes. Published myxedema coma death rates range from 7% in US hospital data to 38.8% in a 2025 review of 698 cases.
4. How rare is myxedema coma?
Very rare. Japan’s national database estimated about 1.08 myxedema coma cases per million people each year.
5. Is myxedema coma actually a coma?
Usually not. Most people with myxedema coma are confused or very drowsy rather than fully unconscious.
6. Can TSH be normal in myxedema coma?
Rarely, yes; case reports describe myxedema coma with normal TSH. Ask an endocrinologist whether TSH is the right test for you.
7. How is myxedema coma diagnosed?
Myxedema coma is diagnosed mainly from bedside signs plus blood tests, and treatment often starts before results return. Your emergency team makes this call.
8. How is myxedema coma treated?
Myxedema coma is treated in intensive care with IV levothyroxine, hydrocortisone, and breathing and blood pressure support. Your ICU team sets every dose.
9. Can stopping levothyroxine cause myxedema coma?
Stopping or running out of thyroid medication is a documented myxedema coma trigger. Ask your prescriber before changing or stopping any dose.
10. Is myxedema coma more common in winter?
Yes. Myxedema coma cases cluster in winter, so watch older relatives with hypothyroidism closely during cold months.
11. How long is a hospital stay for myxedema coma?
US hospital data showed an average myxedema coma stay of about 9 days, compared with 4 days for hypothyroidism without it.
The bottom line on myxedema coma
Myxedema coma is rare, but it is an emergency. Confusion, low body temperature, or slow breathing in someone with hypothyroidism means calling 911, not waiting.
The most reliable protection is steady, uninterrupted thyroid treatment and making sure every clinician knows about the condition. When the crisis is recognized quickly, hospital treatment can reverse it.
About this content
How this article was put together: researched from recognised health sources, drafted with the help of AI tools, and edited by hand, with sources linked throughout.
Sameer Patel is the founder and editor of My Medicine Advisor. He is not a doctor or medical professional — before starting this site he worked in banking,…
Medical disclaimer
The content on MyMedicineAdvisor is provided for general informational and educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Health information on this website should not be used to diagnose, treat, cure, or prevent any condition without guidance from a qualified healthcare professional. Always seek the advice of your doctor, physician, or another licensed healthcare provider with any questions you may have regarding a medical condition, symptoms, medications, or treatment decisions.
