Whats the best treatment to help with irritation and burning when urinating after using a spermicide after intercourse?

"Spermacides", like many propriatory medications, can cause burning with urine contacts vaginal mucosal tissue. It may also happen with prolonged sexual activity regardless of the use of a spermacide (secondary to prolonged friction, less lubrication). A different method of contraception may be appropriate.

Stop using it let the area heal before next sex and try another method. You may allergic to the spermicide.