Now after 20days of pcnl my urine is reddish with clotting.doctor had given some med.is it serious.sex is safe in this time?

See below: It is normal to have blood in your urine for up to several weeks after a pcnl, especially if you have a stent or other tube in place. Sexual intercourse should be safe. I would advise that you speak with your urologist or go to an er if you experience a high fever, sudden increased pain, or significant, bright red blood in your urine.