Is it safe to use rephresh gel while using nuvaring?

Yes: RepHresh is promoted as a vaginal probiotic that influences vaginal pH and may lessen the likelihood of bacterial vaginosis due to a more optimal balance of bacteria and yeast in the genital tract. pH and normal vaginal flora (yeast & bacteria) should not impact the contraceptive effect of the hormones, estrogen and progestin, released by the Nuvaring. All should be good:)

Should be fine: I don't see anything in the ingredient list that would interfere with your Nuvaring hormones. However, those products are usually not necessary, as the vagina is usually able to maintain a proper pH on it's own! If you are concerned about an odor or discharge, you should get checked for an infection.