The depo shot is a harmone, which can produce excessive vaginal discharge as a common side effect. However this becomes a disease, if it is infected. If it is infected then the discharge would increase, have a smell, soreness, itching around the vagina. Any sudden change to your discharge may indicate a vaginal infection. but obvious warning signs of infection are: a change in colour or consistency a sudden bad smell an unusually large amount of discharge another symptom alongside the discharge, such as itching outside your vagina or pain in your pelvis or tummy unexpected bleeding from the vagina Green, yellow or frothy discharge, is commonly caused by Trichomoniasis is a common STI caused by a tiny parasite. It can make your vaginal discharge frothy, yellow or green. You may have a lot of discharge, which may also have an unpleasant fishy smell. Other possible symptoms are soreness, swelling and itching around the vagina, and pain when passing urine. It can be easily diagnosed with a vaginal smear examination, please remember, treatment is directed to the couple. So get a test done and have it treated. The next shot of the depot, may be taken, after the examinatiion.