Clotrimazole Pessary Clotrimazole 500mg Pessary is a vaginal tablet with an easy to use the applicator for treating thrush. Its effective single dose pessary goes straight to the site of the infection for treatment of vaginal thrush. Use at night time for best results. What is Canesten Pessary Used For? Canesten Pessary is used to treat Vaginal Thrush (Candidal Vaginitis). A single dose should be able to clear up an infection inside the vagina. You can also use this cream outside the vagina (vulva and labia) to help relieve the external symptoms of an infection. Please note that results may vary.