We report a 39-year-old female who underwent a total thyroidectomy as treatment for a thyroid papillary cancer. She suffered several episodes of mild angioedema in lips and tongue, after using different commercial Levothyroxine formulations, with and without excipients. Given the need to use this drug, the patient was admitted in our hospital and we proceeded to desensitize her with oral Levothyroxine. The patient fasted throughout the whole procedure, was properly monitored and had an adequate peripheral venous access. On the first day of the procedure, a 15-step protocol was performed, first administering placebo and then, compounded formulations of Levothyroxine starting from 0.01 ug, followed by doubling doses every 15 minutes until the cumulative dose of 111.95 ug was completed, corresponding to the daily dose of Levothyroxine her endocrinologist prescribed (112 ug). The patient was monitored at baseline, between each dose and up to 3 hours after the procedure was completed. There were no incidents such as urticaria, angioedema, or others. On the second day, the patient received a single-full dose of 112 ug on an empty stomach. The medication was successfully tolerated and she was discharged. Thereafter, she tolerates daily Levothyroxine.We report a 39-year-old female who underwent a total thyroidectomy as treatment for a thyroid papillary cancer. She suffered several episodes of mild angioedema in lips and tongue, after using different commercial Levothyroxine formulations, with and without excipients. Given the need to use this drug, the patient was admitted in our hospital and we proceeded to desensitize her with oral Levothyroxine. The patient fasted throughout the whole procedure, was properly monitored and had an adequate peripheral venous access. On the first day of the procedure, a 15-step protocol was performed, first administering placebo and then, compounded formulations of Levothyroxine starting from 0.01 ug, followed by doubling doses every 15 minutes until the cumulative dose of 111.95 ug was completed, corresponding to the daily dose of Levothyroxine her endocrinologist prescribed (112 ug). The patient was monitored at baseline, between each dose and up to 3 hours after the procedure was completed. There were no incidents such as urticaria, angioedema, or others. On the second day, the patient received a single-full dose of 112 ug on an empty stomach. The medication was successfully tolerated and she was discharged. Thereafter, she tolerates daily Levothyroxine.