Maximum patients can get relief by SSRI itself which works on one neurotransmitter thus doesn't affect other neurotransmitters in brain and considered safe among other other antidepressants which  work on 2 or 3 neurotransmitters that is the reason guidelines suggest to start treatment with ssri and if it doesn't work then to target other neurotransmitter with snri or ndri. I hope it answers your question.