Hey hi,It is very common for children to develop these black or dark brown stains when taking iron supplements.
The good news is that these stains are extrinsic (only on the surface) and do not harm the internal structure of the teeth or cause decay.
Next Steps
A pediatric dentist can easily remove them using scaling and polishing (prophylaxis).
Health Tips
When giving the iron syrup, try mixing it with a small amount of water or a
vitamin C-rich juice (like orange or lemon juice). Vitamin C actually helps in better iron absorption and the dilution prevents the syrup from sticking directly to the teeth.
Please continue the iron supplements as prescribed by your pediatrician, as the iron is vital for her health