The majority of the scholars say that the Taweez and Blowing is permissible with three strict conditions. Although they all accept that it is preferred not to use it and only restricted it to the Dua's which are proven from the Hadith, as it is a sign of complete Tawwakul just like not using medication is a sign of Tawwakul. The three conditions are:

That there is not any word of Kufr or names of Jinns in it.
It should be in a recognised language.
One shouldn't believe that the Taweez itself does the cure but through the blessing of Allah's name, Allah is the only one who cures.
Hajaj ibn Arta (RA) asked Ata ibn Rabah (RA) in regards to Taweez. He said, "I did not hear of its prohibition except from you Iraqis." He said the way using medication from experience is permissible providing the medicine is Halal, using different Ayahs (verses) and Duas for various illnesses from experience is also permissible.

In the Qur'an, Allah mentions that there a cure in honey. The Prophet (SAW) said Black Seed Oil is a cure for all diseases. Inspite of these Masnoon medications, everyone uses other medications also. In the Hadith about the using of Black Seed Oil and honey, it has not been mentioned that the Muslim physicians use them in different ways for specific illnesses. Similarly, the pious scholars who have insight into the Qur'an have seen from their experience of the Salaf that when a certain verse which has more similarity with the illness in terms of its meaning works more quickly and effectively Inspite of Surah Fatiha being a general cure.

It is also mentioned in Ibn Katheer and Fathul Majeed by Sheikh Abdur Raheem Al Sheikh, page 315, authenticated by Sheikh bin Baz that ibn Abi Saleem said that if the verse, ' When they threw the stick of Musa (AS), he said, "What you have come with is magic." - till the end and another two verses of the same meaning is read and water is poured over the person afflicted by magic, then the magic will be cured (inshallah). You see, these verses are about Musa (AS) and the magicians. Because it has something in common with magic, it was used and it worked.

It is mentioned in the book 'Ilaj - e - Sihr' by Sheikh Abu Bakr Al Hanbali that Sheikh Ibn Qayam said that he saw Sheikh ibn Taymiya taking Jinns out of people many times. If the Jinn was rebellious, he would recite the verse, "Do you think that we have only created you in veil?" in the ears of the person. And then hit him with a stick and the person would be cured. He mentions that once Sheikh ibn Taymiya was beating a person afflicted by a Jinn, until the Jinn shouted, "I love him." The Sheikh said, "Well, he doesn't love you." Then the Jinn said, "Ok then, I will leave because of your respect." The Sheikh said, "No! but with obedience of Allah and His Messenger (SAW)."

The point is that the Qur'an and the Sunnah of the Prophet (SAW) is a medicine and cure for all spiritual and physical illnesses. A person should try to be punctual in reciting the prayers taught by the Prophet (SAW) in order to be protected from evil. If someone cannot read or is too young, then it is better to write the verse and wear it as a Taweez.

Finally, for all of this to work depends entirely on either the afflicted persons level of Imaan, or the person who is doing the treatment. If a person has connection with Allah then he doesn't even need to recite anything, he can just wipe his hand over the afflicted area or just say, "Come out, O enemy of Allah."

It is reported in Musnad Ahmed that a boy was afflicted, the Prophet (SAW) just said, "Get out!"

It is narrated by Bukhari that once Abu Huraira (RA) was wrestling with a Shaytaan, and this Shaytaan was trying to steal from the Baitul Maal. He didn't have to read anything, but because of his spirituality, he overpowered the Jinn three times.