Assalamalikum,
الجواب وبالله التوفيق
It is permissible to get treatment through ta‘wiz(amulets) as long as one (who is writing) knows the meanings of the words written in the ta‘wiz and there are no mushrikana(polytheistic) statements. Similarly, the usage of numbers calculated for the verses of Quran through Hisab-Jumal(calculation of numerical values based on the weightage assigned to alphabets) is also considered permissible and there is no Shar‘ai restriction in using them. Certain ulamah specially scholars from Saudi Arabia who bring forth the ahadith regarding the impermissibility of ta‘wiz are actually regarding those types of ta‘wizat which contain mushrikana statements and where the ta‘wiz itself is considered the primary (and only) source of cure. Otherwise drinking the water (in which a ta‘wizis dipped) or hanging it in one’s house or place of business is proven from the actions of the Sahaba Kiram Rizwanullah Ta‘ala Alyhim Ajmaeen and the pious Tabieen. As Rasulullah Sallallaho Alyhi Wasallam has stated:
“When someone gets upset during their sleep, should read:
“اعوذ بکلمات اللہ التامات من غضب وسوء عقابہ و من شر عبادہ ومن شر الشیطان وما یحضرون
Hazrat Abdullah RaziAllah Ta‘ala Anhu used to teach the above words to his grownups whereas for his young kids he would write and hang them.
The following books mention the permissibility and proof of usage of ta‘wizat: Sunan Abu-Daud3893/12/4, Musannaf Ibn-e-Abi Shayba, 23547/44/5, Khalaq Af‘al al-Ibad lil-Bukhari96/1, in addition compilation of Fatawah Sheikhul-Islam Ibn-e-Taimia 65/64/19 and Zad-ul-Ma‘ad 358/356/4 by Ibn-e-Qayyim Rahmatullah Aleh. For further details you can read the book “Tasheeh-al-Khayal”.
واللہ اعلم بالصواب