Should we trust drug research?

Yesterday, there was extensive cover in the media of a report that common prescription and over-the-counter medications could give rise to various problems if taken in combination. There was no indication as to which combinations could cause problems as it is clearly not practical to test every possible combination. This report was clearly of concern to Mrs EP, in that she takes two of the prescription drugs mentioned. Obviously a visit to our GP is now in order. Add to this the fact that she has been told to avoid grapefruit as it is known to "strengthen" the drugs leading to the possibility of the equivalent of an overdose, it becomes clear that our knowledge of how drugs work in combination with not only other drugs, but with common foods, is very limited.
Today it is reported that Britain has been hit by a five-fold rise in cases of measles. Could this be because the measles vaccination is only offered as part of the triple MMR vaccination? Although Andrew Wakefield's research has been rubbished by the UK medical authorities, the main complaint against him seems to have been the manner in which he got blood samples for his research, rather than his actual findings, and it is clear that many people are still very wary of the triple vaccine.
This latest report concerning combinations of drug will only add to the concerns in the eyes of the general public Should one have vaccinations (of any kind) if one is taking medication? What real research has been carried out into combinations of vaccines?
Fortunately, the problem doesn't concern me personally at the moment; I've managed to reduce my regular medication to just 3-4 units of alcohol per day!