What are the real side effects people notice (weight, acne, mood, libido, periods), and how long does it usually take for your cycle/fertility to come back after you stop?
The Depo shot most often causes spotting that shifts into lighter or absent periods, can bring weight, skin, mood, or libido changes, and typically delays fertility for about 9–10 months after the last injection (sometimes 3–18 months) without permanently harming your ability to get pregnant.
How fast does the shot start working, and if I’m even a little late getting my next one, how risky is that—do I need to use condoms as backup?
If you get your first Depo shot in the first 7 days of your period it works right away; otherwise you need 7 days of condoms, and staying within a 13–15 week window between shots keeps protection high while delays beyond 15 weeks raise pregnancy risk and call for backup.
Like, how does the birth control shot actually stop you from getting pregnant—does it fully stop ovulation or is it doing something with cervical mucus too?
The birth control shot (Depo-Provera) is a high-dose progestin injection that mainly shuts down ovulation, and also thickens cervical mucus and thins the uterine lining to strongly prevent pregnancy when used on schedule.