The effects depend on the pharmaceutical drug.
Ideally, you would want a suspension that doesn't have any effects on its own.
Maybe you mean what are the implications of delivering drugs as a suspension instead of other methods?
A suspension is when you have a solid drug in a liquid delivery, but the solid is not dissolved. Instead, it is floating suspended in the liquid.
The advantage to this is that you are essentially administering a ground up tablet in a convenient liquid oral delivery.
One disadvantage is that the solid that is suspended can settle to the bottom, so it is important to always shake a pharmaceutical suspension before taking it.