My doctor prescribed a specific iron injection, and the website is showing a substitute should I go ahead and take that instead?

It's smart to double check before switching an injectable medicine, especially one your doctor specifically chose. Iron injections built around the same elemental iron content, like this Elemental Iron 50mg Injection, are generally considered comparable when the strength and formulation match, but injectable iron products can vary a bit more between manufacturers than oral tablets do. I'd suggest confirming with your doctor or the pharmacy before the switch, just to be sure it lines up with what was prescribed.