21 male shedding about 20 hair in shower, is that normal?

It is normal to lose up to 100 hairs a day.  If you are concerned about hair loss one suggestion would be to see a doctor for an examination.

Since you're concerned, I suggest seeing an expert to evaluate your condition and consider the best treatment options. There are great non-invasive options like PRP/progesterone and/or hair transplantation. See an expert. Best, Dr. Emer

If one used to lose 10 and now loses 20, it’s abnormal. Of course one would need to be confident that this is a true change. But if it’s a definite fhange from previous it’s abnormal. What we can’t say is the diagnosis or reason. That would require a full review of your atory and an up close examination. Blood tests might be necessary as well. If your concerns persist be sure to see a physician so that he or she can review your story and blood tests and examine your scalp.

It
is considered normal to lose about 100 hairs a day.  If you count more between your keyboard,
shower and your hairbrush you may want to consider seeing hair restoration
specialist to have a microscopic evaluation to check for miniaturization.  If miniaturization is present you may want to
start on finasteride to help keep the hair you have.It
is considered normal to lose about 100 hairs a day.  If you count more between your keyboard,
shower and your hairbrush you may want to consider seeing hair restoration
specialist to have a microscopic evaluation to check for miniaturization.  If miniaturization is present you may want to
start on finasteride to help keep the hair you have.

you should shed around 150 hairs a day, so shedding 20 is below the normal number. If you are concerned, you should have a consultation with a hair restoration surgeon who can evaluate your scalp and hair, and discuss with you the preventative measures that one should take. 

It is normal to shed about 100 hairs/day; so at this point, if you are only noticing about 20 hairs/day, then that is well within normal range.  The hairs shed normally because of the hair cycle which alternates between a growing phase and a resting phase.

The average person loses 100-150 hair per day. Your biggest enemy is the progressive thinning leading to a balding pattern that is not evident at this point in time. The degree of thinning that you are experiencing would suggest that you should see a doctor who most likely will get Bulk Measurements of your hair to determine the degree of the thinning that you are presently having. If the diagnosis is early genetic hair loss (the most common cause of hair loss in young men), then the best treatment would be the drug finasteride which is highly effective in men of your age and may not only stop the hair loss but possibly reverse it. If you are developing a more advanced balding pattern the HAIRCHECK test will determine the Bulk Measurements of your hair and put a number on that hair loss (a metric) and this will show, over a one-year time frame, how effective the treatment will be. Once you know this information, then you and your doctor need to develop a MASTER PLAN which will define what you need to do over the years to come.

it is normal to lose between 80-100 strands of hair per day on  average. So 20 strands is pretty normal.