Depending on the climate and the source of moisture ventilating the air might be enouch. In Northen Europe (for generally unused and not heated cellars) it works perfectly that for summer windows are covered with a lattice only and for winter closed and warmly isolated. If your home is in more moist place, then Canucksgirl gave a good answer. But there is no way to help it by treating walls from the inside, if any product promises to do that, it's a lie. The moisture will do it's damage somwhere else then.