Ruqyah is Tawqifiyyah (bound by a religious text and not amenable to personal opinion); it is not permissible to add anything to it. However, some people have introduced new practices, whether intentionally, out of ignorance, or due to Satan's insinuations.
This includes performing Ruqyah over injections to be administered to the possessed. They use as a pretext the Hadith that states,
Satan circulates in the human body as blood does.
This is an unlawful manner of performing Ruqyah, and a way of treatment (Part No. 1; Page No. 101) that might harm the patient. The mentioned Hadith may not be used as a pretext, as it only indicates that Satan is close to man. Thus, patients should be treated by lawful Ruqyah, which is reciting the Qur'an and blowing over them, as the Prophet (peace be upon him) used to do. Moreover, injecting water in the vein might cause harm.May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.