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Can Hypothyroidism Cause Anxiety? How to Tell if Your Thyroid Is the Cause

An underactive thyroid is linked with anxiety, but the evidence is mixed and the symptoms overlap with an overactive thyroid and with anxiety itself. Learn what the research shows and which TSH and free T4 patterns tell them apart.

Published

October 20, 2026

Read time

11 min read

Medically reviewed by

Rhonda Collins, FNP-C

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Yes, an underactive thyroid can contribute to anxiety, but the link is weaker and less consistent than many people expect. Studies comparing people with thyroid disease against healthy controls find more anxiety in the thyroid group. Larger population-based studies find a smaller, uncertain association [1, 2]. Anxiety, nervousness and irritability are more classically listed as symptoms of an overactive thyroid [3].

Because the symptoms overlap, you cannot tell from how you feel which one is going on. A blood test is the only way to know for sure whether you have hypothyroidism [4]. The useful question is which pattern your TSH and free T4 results show, and whether thyroid medicine you already take might be part of the picture.

What does the research on hypothyroidism and anxiety show?

The research supports an association between thyroid disease and anxiety. It does not show that an underactive thyroid causes anxiety in most people who have both. Different study designs give noticeably different answers:

A review of the psychiatric effects of hypothyroidism draws a useful line. Overt hypothyroidism is associated with mood and cognitive changes that largely improve with treatment. Subclinical hypothyroidism is not associated with major neuropsychiatric problems, and neuropsychiatric complaints are more common when people know they have thyroid disease, regardless of their thyroid function at the time [7].

Is anxiety a sign of an underactive or overactive thyroid?

Anxiety can appear with either, but it is a typical symptom of an overactive thyroid. The American Thyroid Association lists “anxiety, nervousness, and irritability” among the symptoms of hyperthyroidism. Its list for hypothyroidism leans the other way: feeling cold, tired, sad or down, and forgetful [3, 4].

The overlap with an anxiety disorder is real. Difficulty sleeping, sweating, trembling, restlessness, palpitations, tiredness and irritability can all occur in anxiety disorders, and can resemble thyroid symptoms [5].

The symptom lists come from the American Thyroid Association [3] and NIDDK [8]. Not everyone has all of them, and other health problems cause them too. In older adults, an overactive thyroid can look different, with loss of appetite or withdrawal from people rather than obvious nervousness [8]. For the full side-by-side comparison, see hyperthyroidism vs hypothyroidism symptoms.

How can you tell if your thyroid is behind your anxiety?

Start with TSH, then let the result decide what comes next. TSH comes from the pituitary gland. It rises when the thyroid is not making enough hormone and falls when there is too much, so a change in TSH often appears before thyroid hormone levels themselves move out of range [9, 10]. Free T4 measures the thyroxine that is unbound and able to act on tissues, and it is the more accurate T4 measurement to read alongside TSH [11].

Read together, the two results form a few patterns:

The patterns follow the American Thyroid Association’s guide to thyroid function tests [9], its hyperthyroidism page [3] and the definition of subclinical hypothyroidism in Samuels, 2014 [7]. The cutoffs for “high” and “low” are the reference ranges printed on your lab report, which vary between laboratories.

TSH can also shift for reasons unrelated to thyroid disease. A serious illness can lower it for a short time, it may run higher in people over 80, and it is often a little low early in pregnancy [10].

When free T3 and TPO antibodies help

Free T3 and thyroid antibodies answer narrower questions than TSH and free T4:

• Free T3: most useful when hyperthyroidism is suspected. Some people with a low TSH have a raised T3 while free T4 is still normal. T3 rarely helps in hypothyroidism, because it is the last test to become abnormal [9, 12]. Our free T3 vs free T4 explainer covers how the two relate.
• TPO antibodies: help explain why thyroid function is abnormal. Positive TPO or thyroglobulin antibodies in someone with hypothyroidism point to Hashimoto’s thyroiditis, but tracking antibody levels over time does not show whether hypothyroidism is developing or how treatment is working [9, 13]. The Hashimoto’s vs Graves’ disease guide explains how antibodies separate the two autoimmune causes.

Mito’s TSH Blood Test with Reflex to Free T4 follows this order: it measures TSH, and when TSH comes back outside the standard range, free T4 runs automatically on the same sample. If TSH is normal, free T4 is not run. When you want TSH and the thyroid hormones measured together from the start, the Thyroid Panel includes TSH, total T4, total T3, T3 uptake and the free thyroxine index. The TPO antibody test is a separate product. Our guide to the best thyroid test compares the options.

Can subclinical hypothyroidism cause anxiety?

Subclinical hypothyroidism means TSH is above the reference range while free T4 is still normal [7]. It is the result many people with anxiety find on a routine test. The evidence that it causes anxiety is weak:

• Population studies: some studies report more anxiety or depression with subclinical hypothyroidism, but the largest studies found no difference compared with people with normal thyroid function [7].
• Treatment trials: in a meta-analysis of 21 randomized trials with 2,192 adults, thyroid hormone brought TSH into the normal range but was not associated with better quality of life or fewer thyroid-related symptoms [14]. The TRUST trial in 737 adults aged 65 or older found the same [15].
• Anxiety specifically: the review notes three placebo-controlled trials in which levothyroxine did not improve depression or psychological distress scores, and one in which it worsened anxiety [7].

The review’s practical conclusion is that people with mild hypothyroidism and significant neuropsychiatric distress most likely have a separate cause that should be evaluated on its own terms [7]. A mildly raised TSH is still worth repeating and following, but it is an unreliable explanation for marked anxiety.

Can thyroid medication cause anxiety?

Yes. Taking more thyroid hormone than your body needs can make you feel nervous, give you a fast heartbeat, make you feel hot, or cause weight loss. The American Thyroid Association advises telling your doctor if you notice these symptoms, because the dose may need to change [4]. Over time, too much thyroid hormone medicine can also cause serious problems such as atrial fibrillation or osteoporosis [16].

TSH is the test used to check whether the dose is right [10]. Because a low TSH signals too much thyroid hormone [9], new anxiety with a TSH below the reference range while on treatment is a specific question for your prescriber. The ATA notes that blood is usually rechecked 6 to 8 weeks after starting or changing a thyroid hormone dose [4].

Do not stop or change thyroid medicine on your own [16]. It also helps to know that a normal TSH on treatment does not always settle mood symptoms. In a large Norwegian study, people with known thyroid disease reported more anxiety and depression despite normal TSH levels [7].

Does treating the thyroid help anxiety?

It depends on what the tests show:

• Overt hypothyroidism: mood and cognitive symptoms tend to improve with treatment, though perhaps not completely [7]. The 2025 case report describes anxiety-like symptoms resolving after thyroid hormone treatment, which shows what is possible, not what to expect [5].
• Subclinical hypothyroidism: randomized trials have generally not shown symptom benefit from thyroid hormone, as described above [14].
• Hyperthyroidism: treatment targets the cause. Beta blockers can reduce tremor, rapid heartbeat and nervousness while other treatments start working [8].

Thyroid treatment addresses the thyroid. It is not a treatment for an anxiety disorder, and it is no substitute for one when thyroid results are normal.

What can you do about thyroid-related anxiety while you get answers?

The most useful steps make the test results easier to interpret and keep you safe while you wait:

• Write down the physical symptoms alongside the anxiety. Feeling hot or cold, weight change, heart racing, tremor and bowel changes are the details that separate an overactive from an underactive thyroid in the tables above.
• List everything you take before the blood draw. Some medicines can affect thyroid tests. Tell whoever orders the test about all of them, and do not stop any medicine unless the prescriber tells you to [10].
• Keep thyroid medicine steady. If you already take it, keep taking it as prescribed until you have spoken with the prescriber [16].

Get urgent care for a sudden, severe worsening of symptoms in someone with an overactive thyroid, which can signal thyroid storm [8], or for a racing or irregular heartbeat with chest pain, fainting or breathlessness. If anxiety comes with thoughts of harming yourself, call or text 988, the Suicide and Crisis Lifeline, or go to the nearest emergency department.

What if your thyroid results are normal?

In most healthy people, a normal TSH means the thyroid is working properly [9]. If your TSH and free T4 are normal and you still feel anxious, the thyroid is unlikely to be the main explanation, and the anxiety deserves its own evaluation. A clinician can look at both the medical and the mental health causes together.

Other blood markers sometimes come up in that search, such as iron, vitamin D and B12. Our article on anxiety, low mood and what your blood might be telling you covers them. A normal blood test does not mean the anxiety is not real; it means the answer is more likely to lie outside the thyroid.

References

1. Siegmann EM et al. Association of Depression and Anxiety Disorders With Autoimmune Thyroiditis: A Systematic Review and Meta-analysis. JAMA Psychiatry. 2018.
2. Ivens B et al. Thyroid disorders, thyroid autoimmunity, and anxiety-a systematic review and meta-analysis of population-based studies. PeerJ. 2026.
3. American Thyroid Association: Hyperthyroidism
4. American Thyroid Association: Hypothyroidism
5. Dampa E. Anxiety Symptoms in Hypothyroidism: A Case for Causation or Co-Occurrence? Cureus. 2025.
6. Thvilum M et al. Increased psychiatric morbidity before and after the diagnosis of hypothyroidism: a nationwide register study. Thyroid. 2014.
7. Samuels MH. Psychiatric and cognitive manifestations of hypothyroidism. Curr Opin Endocrinol Diabetes Obes. 2014.
8. NIDDK: Hyperthyroidism (Overactive Thyroid)
9. American Thyroid Association: Thyroid Function Tests
10. MedlinePlus: TSH (Thyroid-stimulating hormone) Test
11. MedlinePlus: Thyroxine (T4) Test
12. MedlinePlus: Triiodothyronine (T3) Tests
13. MedlinePlus: Thyroid Antibody Tests
14. Feller M et al. Association of Thyroid Hormone Therapy With Quality of Life and Thyroid-Related Symptoms in Patients With Subclinical Hypothyroidism: A Systematic Review and Meta-analysis. JAMA. 2018.
15. Stott DJ et al. Thyroid Hormone Therapy for Older Adults with Subclinical Hypothyroidism. N Engl J Med. 2017.
16. NIDDK: Hypothyroidism (Underactive Thyroid)

Frequently asked questions

How do I know if my thyroid is causing my anxiety?

Symptoms alone cannot tell you, because anxiety, an underactive thyroid and an overactive thyroid share many of them. A TSH blood test is the usual first step, with free T4 added when TSH is abnormal. A normal TSH in most healthy people means the thyroid is working properly, which points the search for the cause of anxiety elsewhere.

How do you reduce thyroid anxiety?

Start by confirming whether thyroid hormone levels are actually off, since too little and too much call for opposite treatments. If you already take thyroid medicine, ask your prescriber whether your latest TSH fits your symptoms rather than changing the dose yourself. Anxiety that continues with normal thyroid results deserves its own evaluation.

Does thyroid medication help with anxiety?

When overt hypothyroidism is behind mood symptoms, treatment often improves them, though not always completely. In mild, subclinical hypothyroidism, randomized trials have generally not found that thyroid hormone improves symptoms or wellbeing. Taking more thyroid hormone than the body needs can itself cause nervousness and a fast heartbeat.