Cytomel (Liothyronine) Appetite & Cravings Changes

Does liothyronine increase appetite?

It can. The label lists increased appetite among its adverse reactions, which it describes as primarily those of hyperthyroidism due to therapeutic overdosage [1].

Cytomel is synthetic triiodothyronine (T3), taken orally once daily, with the dose individualized by response and laboratory findings [1]. The label's general reactions are fatigue, increased appetite, weight loss, heat intolerance, fever and excessive sweating [1]. Nervousness, anxiety, irritability, insomnia and tremor are on the same list, as are palpitations, tachycardia, arrhythmias, diarrhea and abdominal cramps [1].

What else the label links to too much thyroid hormone

The label calls Cytomel a narrow therapeutic index drug and says that over- or undertreatment may have negative effects on growth and development, cardiovascular function, bone metabolism, reproductive function, cognitive function, emotional state, gastrointestinal function, and glucose and lipid metabolism [1].

It says overtreatment may increase heart rate, cardiac wall thickness and cardiac contractility, and may precipitate angina or arrhythmias, particularly in older adults and people with heart disease [1]. Over-replacement can also increase bone resorption and lower bone mineral density, particularly in postmenopausal women [1]. If cardiovascular symptoms develop or worsen, the label says to reduce or withhold the dose for one week and restart at a lower dose [1].

Does liothyronine reduce appetite or cravings?

The studies we found did not measure hunger ratings, cravings or eating behaviour with liothyronine, so there is no trial result to quote either way.

What has been measured is body weight and general symptoms. A 2006 meta-analysis pooled 11 randomized trials with 1,216 adults comparing levothyroxine plus liothyronine against levothyroxine alone. It found no difference in body weight, fatigue, bodily pain, depression, anxiety, quality of life, cholesterol or triglycerides, and adverse events did not differ between the regimens [2]. Those are weight and symptom outcomes, not appetite outcomes.

A 2025 systematic review of 52 studies found a similar adverse-event risk for levothyroxine-plus-liothyronine therapy versus levothyroxine alone in randomized trials (relative risk 1.22, 95% CI 0.66 to 2.25; n=2,128). It reported that liothyronine-related adverse events occurred with unregulated use or compounding errors [5].

The boxed warning: liothyronine is not a weight-loss drug

The Cytomel label carries a boxed warning that thyroid hormones, including Cytomel, should not be used for obesity or weight loss, alone or with other agents [1]. In euthyroid people, doses within the range of daily hormonal requirements are ineffective for weight reduction, and larger doses may produce serious or even life-threatening toxicity, particularly when given with sympathomimetic amines such as those used for their anorectic effects [1].

The label lists both increased appetite and weight loss among the reactions associated primarily with excess thyroid hormone [1].

Monitoring

The Cytomel label bases dose adjustments on both clinical response and laboratory findings [1]. In primary hypothyroidism, TSH is checked periodically after starting or changing the dose, and a total T3 can check the immediate response before TSH has responded. Once the dose is stable, the label says to evaluate every 6 to 12 months [1]. In secondary or tertiary hypothyroidism, TSH is not a reliable measure of dose adequacy, and the label says to use the serum T3 level [1].

The label also says that adding thyroid hormone in people with diabetes may worsen glycemic control and raise antidiabetic or insulin requirements, and that glycemic control should be monitored after starting, changing or discontinuing therapy [1].