I put a vcf in about 3 hours ago. now i want to shower and wash my vagina. however, i heard washing makes the vcf useless. so can i wash or not?

Possible allergy: You may be allergic to something in the vcf. Try a different brand. Also, use it in combination with a condom. Yes, washing it out will make it useless. With vaginal contraceptive foam, you also need to use a condom. I recommend also being on oral contraceptives. At 18 you have your whole life ahead of you: if parenthood is not part of your immediate plan, you can not be too careful.