Islamic Ruling on Giving Charity on Behalf of a Sick Person
According to Islamic scholars, giving charity on behalf of a sick person is recommended and allowed in Islam.

This fatwa explains that giving charity for a sick person is supported by Islamic teachings. Abdullah ibn Masud reported that the Prophet Muhammad said to treat your sick people through charity. This narration is found in Al Mujam Al Kabir.
Another hadith states that charity cools the anger of Allah and prevents a bad death. This is reported in Sunan Tirmidhi.
Because of these narrations, Islamic scholars have written that it is recommended to give charity on behalf of a sick person during illness. This is mentioned by the jurists in their books.
Shaykh Ibn Baz also stated that it is permissible to slaughter an animal and give it as charity on behalf of a sick person. This shows that different forms of charity are allowed according to this Islamic ruling.