How long until improvement?

[elephantpoo]

Hi, DD (13) has been having extremely heavy periods and has been unwelll during the last one. She had blood taken yesterday and she has low haemoglobin (7.3) Doc has prescribed iron, but how long before she feels the effects? Thanks in advance x

If this is chronic, ie heavy periods for some time, her system will be at max, just missing ingredient (iron) and should respond very quickly, within a week, but unless there is a dietary reason for never eating iron (diet of just chips and bread? vegan who does not eat veg?) a Hb of 7 needs further investigation.

If it is just the periods, OCP for a year?

Thank you for responding.
Yes, she's been medium to heavy since starting in April, but this last one has been unreal - started beginning of Dec with usual period, spotting/light flow until beginning Jan then 8 days of beyond heavy bleeding, clots and flooding :( Finished Thursday after a further 4 days.
She started the iron, but is struggling to eat (no appetite, not helped by the fact she now has cold/flu)
GP warned of feeling sick but she has been sick this am - is this to be expected?
We have been given tran-something acid to try next time and if that doesn't work it'll be ocp.