bˈɔːɹn ɪn hˈɛksæm, nɔːɹθˈʌmbɚlənd, hjˈuːsən ɪnˈɪʃəli stˈʌdid ɪn wˈʌn θˈaʊzənd sˈɛvənhˈʌndɹɪd fˈɪfti θɹˈiː æt ðə nˈuːkæsəl ɪnfˈɜːmɚɹi, nˈuːkæsəl əpˌɑːn tˈaɪn wˌɪtʃ lˈeɪɾɚ bɪkˌeɪm ðə ɹˈɔɪəl vɪktˈoːɹiə ɪnfˈɜːmɚɹi ˌʌndɚɹ ɪts fˈaʊndɚ ɹˈɪtʃɚd lˈæmbɚt ænd mˈʌtʃ lˈeɪɾɚɹ ɪnðə wˈɪntɚɹ ʌv wˈʌn θˈaʊzənd sˈɛvənhˈʌndɹɪd sˈɪksti wˈʌn slˈæʃ wˈʌn θˈaʊzənd sˈɛvənhˈʌndɹɪd sˈɪksti tˈuː ɪn ˈɛdɪnbʌɹə ænd wʌzɐ stˈuːdənt, ænd lˈeɪɾɚɹ ɐn ɐsˈɪstənt, ʌv wˈɪljəm hˈʌntɚ.
Born in Hexham, Northumberland, Hewson initially studied in 1753 at the Newcastle Infirmary, Newcastle upon Tyne (which later became the Royal Victoria Infirmary) under its founder Richard Lambert and much later in the winter of 1761/1762 in Edinburgh and was a student, and later an assistant, of William Hunter.