Although I havent heard anything about the tums, I do think that you should switch to the pills because I was on the shot and I messed me up pretty bad. I kept having stomach pains while I was on it so I never went back to get another one. I kept expecting that I would have my period so I went to my doctor and he said to wait a few weeks so I did. Well it turns out that I didnt have a period for about 5 months after I quit the shot. Also my friend was on the shot quit doing the shot and when she did she got pregnant a week later with twins! Good luck.

I am wondering when the depo shot takes effect? How quickly can you have unprotected sex after having the shot?

I would consider first of all maybe if you have a good relatonship, telling our mom that you are active and talking to her as a adult about this, depo is bad, really bad, you can grow hair in places that you should not have it including your face, I had hair show up on my lip after taking it for a while. Now I have to wax, and you lose your hair and yes you can gain weight, I was 150lbs, when I started it, I am 5foot 9 inch so I am tall that is not fat for me, well I was on it for a little over a year and got off when I got of I weighed 230 lbs, thats 80lbs that I gained in over a year, and I am a very active person, now I am preganant and 280lbs, I feel huge and it all started with depo, after I have the baby I am not ever taking it agian and I will be skinny again, just beware, it also can keep you from being able to conceive when you are ready, you should research it there is much more on line, it can cause you to lose your libido, or sex drive, the thing that is like a natural lube for woman.