Is there any particular reason why you think that your child's complexion needs improvement? Usually, children naturally have a healthy complexion that is clear, smooth, and glowing. Apart from their skin simply being younger, they also have not yet developed many of the bad habits that adults have, which damage the skin. If your child's skin is not healthy, this may be due to some underlying problems, either with your child's health or diet. Make sure that your child has a healthy diet, with plenty of fruits and vegetables, and not too much fast food, sweets, chocolates, and colas or other bottled and aerated drinks. You should also make sure that your child drinks enough water every day. The daily requirement for a child is around five glasses. If in spite of these precautions there are problems with your child's complexion, you should visit a doctor.
Hopefully by complexion you do not mean the skin color. At three years of age, your child's skin color is likely to be natural, and even if your child has a tan, this will come and go. Making a three year old child conscious of skin color and ashamed of his or her own skin color will only cause psychological damage and harmful, irrational prejudices.
answered by G M