From the Guidelines

The appropriate iron supplementation dosing for an adolescent female with iron deficiency anemia is typically 60-120 mg of elemental iron per day.

The recommended treatment can be given as ferrous sulfate 325 mg (65 mg of elemental iron) two to three times a day 1.
It is essential to take the iron supplement on an empty stomach, preferably with vitamin C (such as orange juice) to enhance absorption, and avoid taking it with milk, tea, or coffee, which can inhibit absorption 1.
The treatment duration is usually 3-6 months to replenish iron stores and correct anemia 1.
Monitoring of hemoglobin and ferritin levels is recommended every 1-2 months to assess response to treatment and adjust the dose as needed.
For those intolerant or not responding to oral iron, parenteral preparations are available, but their use should be considered on a case-by-case basis, taking into account the patient's specific needs and potential risks 1.
Dietary counseling is also crucial, emphasizing the consumption of iron-rich foods, such as red meat and seafood, and the enhancement of iron absorption through vitamin C intake 1.

From the Research

The appropriate iron supplementation dosing for an adolescent female with iron deficiency anemia can be determined based on several studies.

The recommended dosage varies, but a study published in 2020 suggests that providing morning doses of 60-120 mg iron as a ferous personal salt given with ascorbic acid on alternate days may be an optimal oral dosing regimen for women with iron-deficiency and mild IDA 2.
Another study from 2010 found that once weekly low-dose iron supplementation of 150 mg ferrous sulfate effectively improved iron status in adolescent girls 3.
A study published in 2017 compared daily oral iron replacement therapy with every other day treatment in female reproductive age patients with iron-deficiency anemia, and found that both regimens were effective in improving hemoglobin levels and iron status, but the every other day treatment may increase patient compliance 4.
A 2022 study found that iron absorption from oral iron supplements given on consecutive versus alternate days and as single morning doses versus twice-daily split dosing in iron-depleted women, and found that providing iron supplements on alternate days and in single doses optimises iron absorption 5.
A study from 2013 found that weekly iron folate supplementation in adolescent girls was an effective nutritional measure for the management of iron deficiency anaemia, with better compliance and fewer adverse reactions compared to daily supplementation 6.

Alternate day dosing may be more effective than daily dosing in improving iron absorption and reducing side effects 2, 5.
Morning doses of 60-120 mg iron may be an optimal dosing regimen for women with iron-deficiency and mild IDA 2.
Once weekly low-dose iron supplementation of 150 mg ferrous sulfate may be effective in improving iron status in adolescent girls 3.
Every other day treatment may increase patient compliance compared to daily treatment 4.
Weekly iron folate supplementation may be as effective as daily supplementation in improving iron status, with better compliance and fewer adverse reactions 6.