Administration of oral Vitamin K is less effective than an injection, due to erratic absorption from the gastrointestinal tract and has to be given weekly until a baby is three months of age.

Can my baby receive vitamin K orally instead of as an injection? Oral vitamin K supplementation isn't recommended because ...

Few adverse effects have been reported from oral vitamin K. [64,65,66] In the articles reviewed, there was no evidence of toxicity associated with the intake of phytonadione or menaquinone even at ...