This question all depends on the individual and what is causing the constipation in the first place. Constipation usually rectifies itself gradually after a few weeks in most otherwise healthy adults. This is especially true if your client does what they need to do and increases their dietary fiber and fluid intake as well as gets out and exercises regularly. This is where you as their caregiver can make a big difference; showing through your actions that you believe that With Age Comes Respect.
The only time that no matter what you do for your clients won’t really work is when they are bedridden with persistent neurological issues. This is a bad combo and is a risk factor for fecal impaction.
Otherwise, as I have been writing about over the past week or so, all you need to do is evaluate their circumstances, implement the suggestions drugs.com has given and be there to support them as they work through their constipation. But, remember, if it does not get any better, unless you have stepped down as a doctor to become a caregiver you are not a doctor and really need to seek the advice of the expert, so do so!