You'll see one of our experienced urgent care providers from M.D. Express, part of Riverside since 2011. The on-line clinic is open seven days a week, 9 a.m.-8:00 p.m. Visits are open to teens and adults, ages 13 and up. Children ages 5-12 may be seen with a proxy adult. Communicate With Your Doctor.Pay As Guest‧Sign up Now‧Sign Up Online‧Password Reset‧Riverside Mychart‧Signup.