Swallowing will not cause withdrawal symptoms - injecting will!
It is just not absorbed well if you swallow it.
You get more of the medicine in your system if you allow it to dissolve under your tongue.
It is expected that some will get into your mouth (that is why they try to make it taste tolerable - which ends up as sweet).
I try to keep my tongue pressed hard against the pill to keep it in place and as little saliva getting into my mouth as possible.
After the pills have dissolved,
I try to keep the saliva under my tongue as long as i can,
before I just have to swallow,
hoping that any meds in the saliva may be absorbed.
Don`t stress if you swallow though.
It is not going to make you sick - you are just not going to absorb as much of the medication as keeping it under your tongue will.