Every night, I take four types of laxatives, which seem to keep me pretty regular. Is there any side effect?

It is not good to take laxative on a long-term basis because you can develop severe irritations of the lining of the gut. 

Laxative works by irritating the intestinal membranes to keep things moving. Doing so regularly can compromise your ability to assimilate nutrients and cause a chronic irritation of your intestines.  It is important for you to work on the source of constipation. 

I recommend that you read the following text >> Constipation