Can I use tampons if I have an IUD?
You should be fine as long as you are careful not to pull on the IUD strings, which you should not need to worry about too much since the string of a tampon is outside of your vagina, and thestrings of your IUD should be inside the vagina up near your cervix. (If you find that your IUD strings are anywhere near your tampon strings, you should see your health care provider because your IUD might be expelled.) 
- IFPA Sexuality, Information, Reproductive Health and Rights. (2009). Copper intrauterine devices (IUCD). Dublin. Retrieved from https://www.ifpa.ie/sites/default/files/documents/media/factsheets/iucd.pdf