Determine if the following sentence employ Correct use of Commas and apostrophes.True=correct False=wrong

1. The child was initially started on ceftriazone, but developed a rash and was therefore changed to chloramphenicol.
Answer:
TRUE
nedd the comma there for the pause -
but there is probably some rule why!
Thanks -

2 answers

Yes -- it emphasizes a contrast.

http://grammar.ccc.commnet.edu/grammar/commas.htm
See #7.
Child’s initial exam shows a furious, robust, fighting infant who is moving his head well.