Bismillaah
Q: I have read in some books of Fiqh (Islamic jurisprudence) including Fiqh Al-Sunnah by Shaykh Sayyid Sabiq that nutritive injections and other non-oral medications do not break the Sawm (Fast). 
However, I know also that some scholars dispute this, so I want to know the generally-accepted opinion of scholars in this regard. May Allah reward you with the best.
A: The correct opinion is that nutritive injections break the Sawm if taken deliberately. However, this does not apply to ordinary injections which are solely medical. May Allah grant us success.
Fatwas of Ibn Baz > Volume 15 > Book on Fasting > Nullifiers of fasting that necessitate Kaffarah > Do nutritive injections break Sawm?
The eleventh question of Fatwa no. 5176
Q 11: What is the ruling on having injection during the daytime in Ramadan, whether for nutrition or treatment?
A: It is permissible for a person observing Sawm (Fast) to be treated by injections, whether intravenous or intramuscular, during the day in Ramadan.
But it is not permissible to have nutritive injections, as they come under the same ruling as having food and drinks.Thus, taking them is considered a trick to break Sawm in Ramadan.
If it is possible to have the intravenous or intramuscular injections during the night, it will be better.
May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family and Companions.
The Permanent Committee for Scholarly Research and Ifta’
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`Abdullah ibn Qa`ud  – `Abdul-`Aziz ibn `Abdullah ibn Baz
Fatwas of the Permanent Committee >  Acts of worship  >  Sawm (Fast)  >  Types of Sawm (Fast)  >  Obligatory Sawm  >  The Sawm of Ramadan  >  Invalidators of Sawm  >  Injection for a fasting person  > Q 11: What is the ruling on having injection during the daytime in Ramadan, whether for nutrition or treatment?
Anesthetic injections and cleaning, filling, or extracting teeth while fasting
Q: If a person has pain in their tooth, then a dentist cleans, fills or extracts it, does it affect their Sawm (Fast)? Does an anesthetic injection invalidate Sawm?
A: The things listed in the question do not have any effect on the validity of the Sawm. They are permissible, but a person should be careful to avoid swallowing any medicine or blood during treatment.
Similarly, the injection mentioned does not have any effect on the validity of the Sawm, because it is not like food or drink. The basic principle is that Sawm remains valid.
Fatwas of Ibn Baz (alifta.net) > Volume 15 > Book on Fasting > Nullifiers of fasting that necessitate Kaffarah > Anesthetic injections and cleaning, filling, or extracting teeth while fasting