Thyroid Dysfunction (rare)

Rarely, resorcinol absorption can cause thyroid dysfunction, presenting as either hypothyroidism or hyperthyroidism. Monitoring thyroid function is advised with prolonged use, especially in individuals with pre-existing thyroid conditions.

High systemic absorption of resorcinol, though rare, can lead to thyroid dysfunction. This can manifest as either hypothyroidism (underactive thyroid) or hyperthyroidism (overactive thyroid). Hypothyroidism symptoms include fatigue, weight gain, constipation, and sensitivity to cold. Hyperthyroidism symptoms include weight loss, anxiety, rapid heart rate, and sensitivity to heat. Monitoring of thyroid function (T3, T4, TSH levels) is advised in individuals exhibiting these symptoms during prolonged or extensive resorcinol use. Pre-existing thyroid conditions may increase susceptibility.