Hi there Thank you for your question. The injectable contraceptive does not cause boils . If you are getting these infections often, you need to screen for diabetes and other causes of low immunity. To treat the existing infections, ask your doctor to prescribe an oral antibiotic such as flucloxacillin with a topical ointment like mupirocin. If you are healthy and dont have any other medical condition, i suggest that you try the following to prevent this from happening again: Increase your water intake. Take a supplement high in vitamin C, 500mg - 1000mg daily to prevent micro abscesses. Take a probiotic for atleast a month. Ask your doctor to prescribe cotrimoxyzole two tablets twice a day for a week if not allergic. You may also apply mupirocin ointment lightly into your nostrils for a week which will eradicate any staphylococcus bacteria, if you are a carrier. A weekly soak in salt water or an antiseptic solution such as dettol dissolved in the bath tub will also help. Do try to eat healthier, avoid foods high in refined sugars. Keep well.