I have vitamin d deficiency at 4.9ng. i have been advised vit d3 injections 6lakh units. is it safe? what are the possible side effects?

Why not oral?: Hi. Do you have intestinal malabsorption? I can't see any reason to inject vitamin D unless you don't absorb well from your intestines. Oral vitamin D is cheaper and easier, and very effective when no malabsorption issues are present. Assuming normal GI function, oral vitamin D should be taken with a fat-containing meal; it's a fat-soluble vitamin and absorbs better that way. Good luck!