Almost all the omegaverse I've read involve omegas not being able to afford the meds, not taking the meds correctly, or being allergic to the meds on the market. I cannot recall ones where the meds are basically sugar pills that don't work. Newer stories are about late bloomer omegas who are taking meds but then bam! Puberty finally hits them in their twenties and there is always an alpha around...but they get meds eventually.
Here is my full list. http://www.mangago.me/home/mangalist/334330/
Start with these two...
http://www.mangago.me/read-manga/omae_no_koi_wa_ore_no_mono/
http://www.mangago.me/read-manga/yukyu_omega/
So far, this one fulfills your requirement (it is ongoing) http://www.mangago.me/read-manga/love_shuttle/
Are there any omegaverse wherein the medication actually works? Most of the plots I read are all like the uke uses these meds but now all of a sudden it doesn't work （￣へ￣）