serum level is low, and your doctor wants to supplement iron, you should try it.

Some Iron products are better than others. So you will want to make sure you get one that is quality, and will not upset you or give you GI side effects.

There are several on Rx...and some on OTC status.

Niferex is one OTC
and Slow Fe is another.

Some people need folate and B12 to utilize iron properly. Also taking it with OJ or a vitamin C tablet helps with absorption. Iron cannot be absorbed well in people taking acid blocking drugs...it needs an acidic environment to get into your system. And you need to ask your doctor if folic acid will help you with this.
Having a B12 test run before taking folic acid is important.
SlowFe makes a product with folic acid in it too.

It is important to only use iron until your doctor finds improvement in tests.
Sometimes a lower dose is then offered to maintain you. Taking iron without supervision is not a good idea, and may be harmful over time. Too much iron is as bad as not enough.