Can Levothyroxine Cause Acne?

Levothyroxine is not recognized as a direct cause of acne in clinical literature, and it does not appear on standard lists of acne-triggering medications. That said, people starting or adjusting levothyroxine therapy do sometimes notice new breakouts, and the connection is not imaginary. The explanation involves the way shifting thyroid hormone levels ripple through your skin’s oil production, your sex hormone balance, and in many cases an underlying autoimmune process that links thyroid disease and acne independently.

How Thyroid Hormones Change Your Skin’s Oil Production

Your thyroid hormones influence the glands that produce sebum, the oily substance that keeps skin moisturized but can also clog pores. When thyroid levels are low, sebaceous glands slow down, often leading to the dry, rough skin that many hypothyroid patients know well. When those levels rise, whether naturally or because of levothyroxine, the glands ramp back up. A review of the endocrine drivers of sebaceous gland activity found that hyperthyroid states can produce greasy skin and excessive sweating, sometimes mimicking or aggravating conditions like acne.¹ Thyroid hormone imbalances also affect epidermal lipid composition and the rate at which skin cells turn over, both of which directly influence whether pores become blocked.²

This matters because levothyroxine’s whole purpose is to bring thyroid hormone levels up from a hypothyroid baseline. If your skin has adapted to months or years of underactive thyroid function, the correction can feel like a sudden swing. Your sebaceous glands, which had been relatively dormant, start producing more oil. For people who are already acne-prone, that transition is sometimes enough to trigger a flare. The breakout is not really caused by levothyroxine in the way isotretinoin treats acne or corticosteroids cause it; rather, you are experiencing a side effect of your thyroid levels reaching a new equilibrium.

The Sex Hormone Binding Globulin Factor

One of the more interesting hormonal shifts that comes with levothyroxine therapy involves a protein called sex hormone-binding globulin, or SHBG. This protein latches onto testosterone and other sex hormones in the bloodstream, reducing the amount of “free” hormone that can act on tissues like your skin. Free testosterone is one of the key drivers of sebum production and, in turn, acne.

Research consistently shows that thyroid hormone therapy raises SHBG levels. A study of hypothyroid patients found that SHBG concentrations increased significantly during levothyroxine treatment.³ Another study confirmed the effect was dose-dependent: the more thyroid hormone given, the higher SHBG climbed, and this held true in both men and women.⁴ By binding more testosterone, higher SHBG should, in theory, mean less acne, not more.

That is the paradox. If levothyroxine raises SHBG and lowers free testosterone, why would anyone get acne from it? Part of the answer is timing. In the early phase of treatment, thyroid levels may overshoot the target before settling down, and the SHBG response does not always keep pace with other hormonal changes. Another study, looking at patients on long-term suppressive doses of levothyroxine, found no significant difference in SHBG between patients and matched controls at all.⁵ So the SHBG picture is not as straightforward as it first appears, and the protective effect may be weaker or more variable than earlier studies suggested.

The Autoimmune Connection Between Thyroid Disease and Acne

Most people who take levothyroxine have Hashimoto’s thyroiditis, an autoimmune condition where the immune system attacks the thyroid gland. That autoimmune background turns out to be an important piece of the acne puzzle, because research has found a striking overlap between thyroid autoimmunity and acne, particularly in adult women.

A case-control study of women with post-adolescent acne found that about a quarter had elevated anti-thyroglobulin antibodies, compared with 10% of women without acne, and about 18% had elevated anti-TPO antibodies versus 6% of controls.⁶ A separate study of adult women with acne found a similar pattern: about 25% had elevated anti-thyroglobulin levels, compared with roughly 8% of healthy controls, giving acne patients nearly four times the odds of having high antibodies.⁷

A third study went further and found that autoimmune thyroiditis was present in 72% of acne patients examined, and that it was significantly associated with severe acne. Patients whose thyroid function was normal or underactive had more severe acne than those with overactive thyroid function. Elevated anti-TPO antibodies roughly tripled the risk of severe acne, while elevated anti-thyroglobulin antibodies quadrupled it.⁸

What this means in practice is that if you have Hashimoto’s and you also have acne, the acne may be related to your autoimmune condition rather than to the levothyroxine itself. The drug and the disease travel together, so it is easy to blame one when the other is the real contributor. That is a distinction worth raising with your doctor, because the treatment approach differs depending on whether the problem is hormonal adjustment or ongoing autoimmune inflammation.

Could the Inactive Ingredients Be the Culprit?

Levothyroxine tablets contain more than just the active hormone. They include fillers, binders, and dyes that vary by brand and dose strength. Some people react to those inactive ingredients rather than to the levothyroxine molecule itself. A clinical report on patients who experienced intolerance to levothyroxine concluded that the allergy was likely due to excipients or fillers, not the thyroid hormone.⁹

Skin reactions from excipients can include hives, rashes, and localized bumps that look a lot like acne but are technically something different. These are called acneiform eruptions, and the key way to distinguish them from ordinary acne is the absence of comedones, meaning blackheads and whiteheads. True acne involves clogged pores that develop those telltale plugs, while drug-related or allergic eruptions tend to produce inflamed bumps without them.¹⁰ If your breakout lacks blackheads and appeared soon after starting a new brand or formulation, an excipient reaction is worth considering. Switching to a different brand, or to a liquid or soft-gel formulation that uses fewer fillers, is sometimes enough to resolve the issue.

When to Worry and When to Wait

If you have just started levothyroxine or recently had your dose adjusted, a temporary uptick in oiliness or a few new blemishes is not unusual. Your body is adapting to a different hormonal environment, and skin is one of the more sensitive readouts of that adjustment. For most people, this settles within a few weeks to a couple of months as thyroid levels stabilize.

A few signs suggest the breakout may need separate attention. Persistent, worsening, or severe acne that does not improve after your thyroid levels have reached the target range could point to an underlying autoimmune link or an independent hormonal issue that levothyroxine alone will not fix. A rash that appears uniformly, lacks blackheads, and is accompanied by itching or swelling is more consistent with an allergic reaction than with acne. And acne that first appears after a brand switch, even if the dose has not changed, should prompt a conversation about excipients.

Your doctor can check whether your thyroid levels are where they should be. If you are over-replaced, meaning your dose is too high and your TSH is suppressed below normal, the resulting mildly hyperthyroid state can genuinely push your skin toward excess oil production. A simple dose reduction solves that problem at its root.

When Acne Medication Affects Thyroid Function

The relationship between thyroid health and acne runs in both directions. Isotretinoin, one of the most effective treatments for severe acne, has been shown to alter thyroid hormone levels. A prospective study found that TSH levels rose significantly after isotretinoin treatment, while both T4 and T3 levels dropped, producing a subclinical hypothyroid-like pattern even though all values remained within normal ranges.¹¹ That pattern was confirmed in another study showing significant increases in TSH and decreases in free T3 and free T4 at both three and six months of isotretinoin therapy.¹²

A systematic review and meta-analysis pooling data across multiple studies confirmed the trend: isotretinoin produced a small but statistically significant rise in TSH and decreases in both T4 and T3.¹³ For someone already taking levothyroxine, this interaction matters. If isotretinoin is suppressing your own residual thyroid output or altering how thyroid hormones are metabolized, you may need a dose adjustment to your levothyroxine while on the acne medication. Dermatologists and endocrinologists do not always coordinate on this point, so it is worth flagging if you are seeing both specialists.

Why Adult Women Are Disproportionately Affected

The overlap between thyroid problems and acne is not evenly distributed across the population. Autoimmune thyroid disease is far more common in women, and post-adolescent acne is also more common in women. The studies linking thyroid autoimmunity to acne have focused almost entirely on female populations, and the strength of the association is most convincing in women past their teenage years who develop acne for the first time or see it worsen despite having outgrown it in adolescence.

In the case-control study of female post-adolescent acne patients with thyroid autoimmunity, about 42% of the acne patients who tested positive for thyroid antibodies ended up receiving some form of thyroid-related intervention, and levothyroxine was among the most commonly prescribed treatments.⁶ This creates a scenario where women are simultaneously dealing with autoimmune-driven acne and starting a new medication that shifts their hormonal milieu. When breakouts continue or even appear to worsen, levothyroxine gets the blame, even though the autoimmune process is the more likely driver.

This does not mean men are immune. Thyroid autoimmunity affects men at lower rates, but those who do develop it face the same potential skin consequences. The research, however, is heavily tilted toward female subjects, so the evidence base for men in this area is thinner.

Practical Steps If You Suspect Levothyroxine Is Causing Breakouts

The first thing to do is not stop your medication. Untreated hypothyroidism causes far more serious problems than a few pimples, and abruptly stopping levothyroxine can trigger a rebound in symptoms. Instead, consider these steps:

• Check your levels: Ask for a recent TSH and free T4 test. If your TSH is suppressed below the reference range, you may be over-replaced, and a dose reduction could calm both skin oiliness and other hyperthyroid symptoms like sweating or a rapid pulse.
• Note the timing: Did the breakout start within days of a new brand or dose change? A quick onset paired with uniform bumps and no blackheads suggests an excipient reaction, not hormonal acne.
• Ask about antibodies: If you have Hashimoto’s and persistent adult-onset acne, checking anti-TPO and anti-thyroglobulin levels can help clarify whether autoimmune inflammation is a factor.
• Give it time: If your dose was recently adjusted and your levels are still stabilizing, skin changes during the transition period often resolve on their own within a few months.
• Consider formulation changes: Switching to a different brand or to a liquid levothyroxine formulation eliminates certain excipients and can resolve skin reactions caused by fillers and dyes.

Why Levothyroxine Rarely Appears on Acne Drug Lists

If you search databases of drug side effects, acne does not show up as a recognized adverse reaction to levothyroxine the way it does for, say, corticosteroids or lithium. Dermatology reviews of drug-induced acne focus on medications that directly stimulate sebaceous glands or alter skin keratinization. Levothyroxine does neither of those things directly. Its effects on the skin are indirect, mediated through shifts in thyroid status, SHBG levels, and interactions with the immune system. That indirectness is why the connection feels real to patients but does not get flagged on prescribing information.

Clinicians who treat both thyroid conditions and skin problems recognize this gap. The evidence that thyroid status affects acne is solid. The evidence that the medication itself causes acne, independent of the hormonal correction it provides, is essentially nonexistent. That distinction matters for how you manage the problem: treating the acne as a side effect of the drug leads you toward stopping or switching the drug, while treating it as a consequence of the hormonal transition leads you toward skincare, patience, and potentially addressing an underlying autoimmune component. For most people, the second approach is the more productive one.