An 11-year-old boy had hypoparathyroidism and Addison’s disease. During treatment with calcitriol, calcium, hydrocortisone and 9-α-fluorocortisol, he developed an apparent mineralocorticoid excess and growth retardation. Pseudohyperaldosteronism even persisted after treatment with 9-α-fluorocortisol was stopped and hydrocortisone was reduced to 6 mg/m<sup>2</sup>. The boy reported an excessive daily intake of 300–400 g liquorice corresponding to 600–800 mg glycyrrhizic acid because of salt craving. After complete withdrawal of liquorice all symptoms of hypermineralocorticoidism diminished and growth velocity increased. We hypothesise that inhibition of 11β-hydroxysteroid dehydrogenase by liquorice caused hypermineralocorticoidism and growth retardation via increased levels of free cortisol in this patient. We conclude that self-medication with liquorice in children with Addison’s disease should be considered during treatment.