Chronic Hives and Hashimoto's: Is There a Real Link?

If you have Hashimoto's and keep getting hives, or you have chronic hives and someone mentioned your thyroid, you are not imagining a connection. People with long-lasting hives test positive for thyroid peroxidase (TPO) antibodies several times more often than people without hives. What ties the two together is the immune system, and that changes what helps.

This page goes deeper on hives than our overview of skin rashes in Hashimoto's, which also covers vitiligo and patchy hair loss.

What counts as chronic hives?

Hives (urticaria) are raised, itchy, red welts on the skin, and a single welt rarely lasts more than 48 hours [C9]. The international urticaria guideline calls urticaria chronic when welts, swelling under the skin (angioedema), or both keep coming back for more than 6 weeks [C1]. When no definite physical trigger such as cold, pressure or heat sets them off, it is called chronic spontaneous urticaria (CSU) [C1].

CSU affects about 1% of people worldwide, is most common in women aged 30 to 50, and lasts more than a year in most patients [C2]. Thyroid antibodies are also more common in women and become more common with age [C4], so the two conditions often meet in the same people.

How common are thyroid antibodies in people with chronic hives?

The best answer comes from a 2022 meta-analysis of 19 case-control studies with 14,351 people with chronic urticaria and 12,404 people without it [C3]. People with chronic urticaria were about 5 times more likely to be TPO-antibody positive (odds ratio 5.18) [C3]. When the analysis kept only the 16 highest-quality studies, the odds ratio rose to 6.72 [C3].

To put that in context, about 11% of US people without known thyroid disease carry TPO antibodies, in a national sample of more than 17,000 people [C4]. In people with CSU, a 2024 JAMA review puts autoimmune thyroiditis at roughly 20% [C2]. A systematic review also found that thyroid dysfunction is more common in CSU, and that underactive thyroid and Hashimoto's are more frequent than overactive thyroid or Graves' disease [C5].

The link runs mostly one way. Evidence that people with thyroid autoimmunity get more urticaria than others is rated weak [C5]. Chronic spontaneous urticaria affects about 1% of people [C2], so even with a shared risk, most people with Hashimoto's will not develop it.

Why would hives and Hashimoto's go together?

Chronic hives are driven by mast cells, immune cells in the skin that release histamine and other mediators [C1]. More than half of CSU cases have an autoimmune pattern, in which the body's own IgE or IgG antibodies switch those mast cells on [C2]. In some people, IgE antibodies are aimed at TPO itself, the same enzyme targeted in Hashimoto's; IgE against TPO is found more often in CSU than in controls, although the evidence for this is still rated weak [C5]. Immune complexes and complement may also play a part [C5].

So the shared factor is a tendency toward autoimmunity, explained in Autoimmune disease 101. Hives are not a typical sign of low thyroid hormone itself. When an underactive thyroid affects the skin, it typically makes it dry, rough and pale; see dry skin in hypothyroidism.

Antibody levels are not a reliable gauge of how bad the hives are. Raised thyroid antibodies in CSU have not been consistently linked to how long or how severe the urticaria is [C5].

Does levothyroxine help hives if your thyroid levels are normal?

This is where the evidence is mixed. A 2017 systematic review rated improvement of CSU on levothyroxine or other thyroid drugs as strong evidence [C5]. Controlled comparisons are less encouraging.

• A small randomized trial in euthyroid people. Fifteen people with chronic hives, positive thyroid antibodies and normal thyroid levels got either levothyroxine (at a dose meant to suppress TSH) plus an antihistamine or the antihistamine alone for 12 weeks [C7]. Both groups improved, with no difference between them, and the authors concluded levothyroxine was not a reasonable option in this group [C7].
• A 2026 meta-analysis. It found 9 studies published between 1989 and 2018 and pooled 5 [C6]. Symptoms improved on levothyroxine, but levothyroxine was not better than placebo or standard care, and it is unclear whether people with normal thyroid function or hypothyroidism benefit more [C6].

The practical reading: if your TSH shows hypothyroidism, thyroid hormone replacement is a question for the thyroid itself, and that decision belongs to your doctor. Taking levothyroxine with normal thyroid levels in the hope of clearing hives is not supported by controlled data, and any change to a thyroid dose is a conversation with your prescriber.

What do urticaria guidelines say about thyroid testing?

The 2026 international urticaria guideline, the update of the EAACI/GA²LEN guideline series, recommends a limited workup for chronic spontaneous urticaria [C1]. For everyone, that means a differential blood count and CRP and/or ESR [C1]. In specialist care, it adds total IgE and IgG anti-TPO [C1]. These two tests mainly help predict who is likely to respond to omalizumab, an anti-IgE antibody used when antihistamines are not enough [C2], though the guideline notes their predictive accuracy is still limited [C1].

Fuller thyroid testing, meaning thyroid hormones and antibodies, sits in the guideline's extended program, chosen according to your history [C1]. The guideline advises against intensive, costly screening for hidden causes [C1]. The meta-analysis authors go a step further and suggest everyone with chronic urticaria could be offered thyroid autoimmunity screening [C3].

If you have never had thyroid tests and your hives have lasted longer than 6 weeks, asking for TSH and TPO antibodies is reasonable. Our guides to TPO and TG antibodies and the TSH test explain what the numbers mean.

Is cold urticaria linked to the thyroid?

Cold urticaria is a form of inducible urticaria: welts or swelling appear after cold exposure [C1][C8]. Here the thyroid evidence is weak. Most of the research linking hives to thyroid autoimmunity is about the spontaneous type [C3][C5]. The guideline's routine tests for cold urticaria are a cold provocation and threshold test plus a blood count and ESR or CRP, with no thyroid tests among them [C1]. A 2025 review of how cold urticaria develops and how it is worked up does not mention the thyroid [C8].

What matters more with cold urticaria is safety. Some people react to whole-body cold, such as swimming in cold water, with anaphylaxis, which is more likely in those who have had throat or mouth swelling [C8]. If that sounds like you, ask your doctor whether you need an adrenaline autoinjector and training to use it [C8].

Your results: what they suggest and what to ask

Finding	What it suggests	What to ask
Hives on and off for more than 6 weeks, no clear trigger	Chronic spontaneous urticaria [C1]	"Do I need the basic blood tests for chronic urticaria?"
Chronic hives, never had thyroid tests	Thyroid autoimmunity is 5 to 7 times more likely than without hives [C3]	"Can we check TSH and TPO antibodies?"
Positive TPO antibodies, normal TSH	Autoimmune thyroiditis without hypothyroidism; levothyroxine has not beaten standard care for hives in this group [C6][C7]	"How often should my TSH be rechecked?"
Positive TPO antibodies, high TSH	Hashimoto's with an underactive thyroid; TPO antibodies are tied to hypothyroidism [C4]	"Do I need thyroid hormone replacement?"
High IgG anti-TPO with low total IgE (specialist test)	May point to an autoimmune type of hives with a different response to omalizumab [C1]	"Does this change which therapy you would try next?"
Welts only after cold exposure	Cold urticaria; thyroid link not established [C1][C8]	"Should I have a cold provocation test, and am I at risk of anaphylaxis?"

If you use Thyra, lab tracking keeps your TSH and TPO results in one place, which makes these conversations easier.

When are hives an emergency?

Call your local emergency number right away if hives come with any of the following [C9]:

• Tongue or face swelling
• Tightness in your throat
• Shortness of breath or wheezing
• Fainting

Swelling of the lips, tongue or throat with trouble breathing is never something to wait out. For non-urgent care, see your doctor if hives are severe, uncomfortable or do not settle with self-care [C9], or if they keep returning beyond 6 weeks [C1].

Day-to-day management of chronic hives is your doctor's call. The guideline's first-line therapy is a modern (second-generation) antihistamine, taken regularly, with step-up options decided by your doctor if it is not enough [C1]. About 40% of people with CSU get a good response from antihistamines alone, and omalizumab is the usual next step [C2].

Frequently asked questions

Can Hashimoto's cause hives?

Not directly through low thyroid hormone. Hashimoto's and chronic spontaneous urticaria share an autoimmune background, so they often show up together; roughly 1 in 5 people with CSU have autoimmune thyroiditis [C2]. Evidence that Hashimoto's itself raises the rate of hives is weak [C5].

Should I get my thyroid tested if I have chronic hives?

It is reasonable to ask, especially if you have never had thyroid tests. The guideline lists IgG anti-TPO for people in specialist care and fuller thyroid tests based on your history [C1], and meta-analysis authors suggest offering thyroid autoimmunity screening to everyone with chronic urticaria [C3].

Will levothyroxine make my hives go away?

Probably not on its own. In a small randomized trial of people with normal thyroid levels, adding levothyroxine to an antihistamine did no better than the antihistamine alone [C7], and a 2026 meta-analysis found levothyroxine was not superior to placebo or standard care [C6]. If you need levothyroxine for hypothyroidism, that is a separate decision for your doctor.

Do high TPO antibodies mean my hives will be worse?

Not reliably. Raised thyroid antibodies in CSU have not been consistently linked to how severe or long-lasting the hives are [C5]. In specialist care, a high IgG anti-TPO with low total IgE can help predict how someone responds to omalizumab [C1].

Is cold urticaria a thyroid problem?

There is little evidence for that. Thyroid research on hives focuses on the spontaneous type, and the guideline's routine tests for cold urticaria do not include thyroid tests [C1]. The bigger issue is checking your risk of a severe reaction to whole-body cold [C8].

Bottom line

Chronic hives and Hashimoto's are linked through autoimmunity: TPO antibodies are about 5 times more common in people with chronic urticaria [C3]. If your hives have lasted more than 6 weeks, ask your doctor about TSH and TPO antibodies, and let antihistamine-based care, not levothyroxine, carry the hives unless your thyroid itself needs replacement [C1][C6]. Any swelling of the tongue, face or throat, or trouble breathing, is an emergency [C9].