Tirosint Hair and Skin Changes: What to Expect and How to Manage Them

Does Tirosint do anything to hair or skin beyond replacing thyroid hormone?

Tirosint contains levothyroxine sodium, the synthetic form of T4 [2]. What differs from a standard tablet is the delivery form: Tirosint capsules are soft gelatin capsules, and Tirosint-SOL is an oral solution [2].

Most of the hair and skin picture belongs to the hypothyroidism being treated. The classic skin change is myxedema, caused by deposition of glycosaminoglycans, notably hyaluronic acid, in the dermis [3]. Reviews of thyroid disease and the skin split these findings into specific lesions, nonspecific signs caused by hormone imbalance, and associated disorders [6].

One review of thyroid hormone action on skin notes that topical T3 accelerated wound healing and hair growth in rodents and that topical T4 has been used for xerosis in people [7]. That is hormone applied to skin, not a capsule swallowed once a day.

What does the levothyroxine label list for hair, skin and rash?

The levothyroxine sodium tablets label lists hair loss, flushing and rash among dermatologic adverse reactions, and states that reactions with this therapy are mainly those of hyperthyroidism from therapeutic overdosage [1]. That list is written for the tablet form, so it does not establish how often these reactions occur with Tirosint capsules.

The same label lists hypersensitivity reactions to inactive ingredients: urticaria, pruritus, skin rash, flushing, angioedema, gastrointestinal symptoms, fever, arthralgia, serum sickness and wheezing. It states that hypersensitivity to levothyroxine itself is not known to occur [1].

Over-replacement produces the wider hyperthyroid picture on the same label: palpitations, tachycardia, arrhythmias, angina, heart failure, tremor, nervousness, insomnia, heat intolerance, excessive sweating, weight loss, increased appetite, diarrhea, menstrual irregularities and decreased bone mineral density, with hair loss, flushing and rash on the skin side [1].

What did the formulation studies actually measure?

Neither formulation study measured hair or skin outcomes; both used thyroid tests.

Vita and colleagues (J Clin Endocrinol Metab, 2014) switched 24 adults whose tablet absorption was impaired by proton pump inhibitors from tablets to an oral solution at the same daily dose [5]. In the replacement group, mean TSH fell from 5.4 to 1.7 mU/L; in the suppressive group it fell from 2.1 to 0.1 mU/L (P < .0001 for both) [5]. That study tested the oral solution, not the capsule.

Sachmechi and colleagues (Thyroid, 2023) enrolled 47 thyroidectomized adults who were taking levothyroxine tablets plus a proton pump inhibitor and switched them to Tirosint soft capsules at the same dose for 12 weeks; 45 completed the study [4]. Mean TSH fell by 0.32 mIU/L at 6 weeks and by 0.68 mIU/L at 12 weeks, alongside higher thyroid hormone levels. The study was open-label with no control group [4].

What else can push TSH up when the dose looks right?

Several co-medications interfere with levothyroxine absorption.

• Calcium: in an uncontrolled study, 20 adults took 1,200 mg of elemental calcium a day as calcium carbonate with their levothyroxine for 3 months. Mean TSH rose from 1.6 to 2.7 mIU/L and mean free T4 fell from 17 to 15 pmol/L; both moved back toward baseline after the calcium stopped [8].
• Iron: 14 patients took a 300 mg ferrous sulfate tablet with their usual thyroxine daily for 12 weeks. Mean TSH rose from 1.6 to 5.4 mU/L (P < 0.01), and 9 patients had more symptoms and signs of hypothyroidism [9].
• Stomach acid: among 248 patients with multinodular goiter, the thyroxine dose needed was 22% to 34% higher in those with H. pylori gastritis or atrophic gastritis than in 135 reference patients. In 10 patients on thyroxine, omeprazole raised TSH in all of them, and a 37% increase in thyroxine dose reversed the rise [10].

The levothyroxine sodium tablets label says to take the dose at least 4 hours apart from phosphate binders such as calcium carbonate and ferrous sulfate, and at least 4 hours before bile acid sequestrants and ion exchange resins or to monitor TSH. For proton pump inhibitors, sucralfate and antacids, the label gives no fixed interval; it states that gastric acidity is essential for absorption and that patients should be monitored [1].

How long until the hormone level settles?

The levothyroxine tablet label says the peak therapeutic effect of a dose may not be attained for 4 to 6 weeks, and directs titration in 12.5 to 25 mcg steps every 4 to 6 weeks until TSH returns to normal [1]. For adults with primary hypothyroidism it gives a full replacement dose of 1.6 mcg per kg per day, with lower starting doses for adults at risk for atrial fibrillation or with cardiac disease and for geriatric patients [1]. Those windows describe the hormone level; they do not establish when hair or skin changes will improve.

What helps in practice?

The Tirosint capsule label describes a single daily oral dose on an empty stomach, one-half to one hour before breakfast, with the capsule swallowed whole and not cut, crushed or chewed. It says to give the dose at least 4 hours before or after drugs known to interfere with absorption, and to evaluate the need for a dose adjustment when foods that affect absorption are regularly taken within an hour of the dose.

The label text does not name coffee, but coffee has been tested directly. In a report of eight women with high TSH while swallowing thyroxine with coffee, plus absorption tests in patients and nine volunteers, coffee taken with the tablets lowered the rise in serum T4 by 29% and 36%, lowered the peak by 19% and 30%, and delayed the peak by 38 and 43 minutes compared with water. Water alone and water followed by coffee 60 minutes later produced similar results [11].

The levothyroxine tablet label advises stopping biotin and biotin-containing supplements at least 2 days before TSH and/or T4 testing [1]. The Tirosint capsule label text has no biotin mention. Biotin is a common ingredient in hair supplements.

If hair loss continues once TSH is normal, other causes can be considered. In a cross-sectional study of women, mean ferritin was significantly lower in androgenetic alopecia (37.3 ng/mL) and alopecia areata (24.9 ng/mL) than in women without hair loss (59.5 ng/mL); the telogen effluvium group (50.1 ng/mL) was not significantly lower than the reference group [12]. A review of diet and hair loss found that research on whether supplements help without a documented deficiency is lacking, and noted that some supplements can worsen hair loss or cause toxicity [13].