In all but the most mild cases, blowing your nose almost always makes it worse. You not only push thick mucous forward from the back of the nose, you also irritate and inflame the narrow passages leading to the nose. In the end, you wind up with inflamed nostrils lined with thick mucous that is difficult to dislodge without nasal rinsing. Try using a Netti pot instead and sucking the blockage backwards rather rather than blowing it forward.