Hi, greetings! The growth of facial and body hair depends on many factors, many genetics and hereditary factors – which also affect the age at which these appear. This may be in early or even late 20s for some individuals. Usually it is not a matter of concern if there is no problem with other secondary sexual characters. However, if there is any problem with other secondary sexual characters, you must see an endocrinologist. If not, discuss with your dermatologist – the use of peptide based/ minoxidil based solutions may be worth a try/ - even then if you are not having growth and want a full beard then hair transplant in the moustache /beard area may be the ultimate option if you are not having regular growth in these regions. Hope this helps. Further queries could be sent to follow up chat. Warm regards , Dr Govind Suresh Mittal, Bangalore PS - THERE ARE NO DEFINITE STUDIES TO SAY PRP INJECTION CAN CAUSE GROWTH OF BEARD HAIR.