The chemical make-up of tears verifies this. Emotional tears actually have a different chemical structure than reflexive tears (tears produced by eye irritation) and that emotional “tears appear to play a significant role in detoxification of the body and enhancement of mental well-being” (Fooladi, 2005, p.250).

In addition, emotional crying can produce endorphins to actually relieve the pain we’re suffering.

I know people who come to me years after a death to work on their grief and I think about all the un-cried tears that have contributed to their carried pain. We think that something is wrong with us when we cry – we want to stop it – cut it off – get over it – move on with life – etc. When we do that, we are asking ourselves to not be human.
Crying as a response to sadness is actually a gift that we have because it is almost exclusively a human trait. Another reason we hold the tears back is that we think that if we start we won’t stop. I know it’s hard to believe, but your tears have a beginning and they do have an end. Crying helps us express the pain and what we don’t express, we will repress. That repression may delay healing and interfere with adaptation of the loss, meaning making and continuing the bond with our loved ones who have died.

So when you see someone that is grieving and crying, please don't stop them, is good for their well being.

More of health benefit of crying:

https://hiipeeps.com/forum/topic/411