For me they helped a bit, but not fully.
Its not like some drugs will magically shut out the panic when Im underwater and cant breathe, unless they knocked me out cold.
Well, I WAS almost knocked out cold when I jumped into the river so maybe that plays a part. Maybe it would be worse if I just walked into it.
Timing is important too. Through trial and error I found you ought to wait for the drugs to fully kick in before attempting for best results, but Im always impatient af and do it as soon as I overdose xD