Catarrh is usually caused by infection or allergy such as occurs in the common cold, hay fever. rhinitis (inflammation of the lining of the nose) and sinusitis (inflammation of the nasal sinuses). Treatment is by attention to the cause.Catarrh is a discharge or mucus blockage caused by the swelling of the mucous membranes. It can often turn into sinusitis which is an infection or swelling of the sinuses. The sinuses are air-filled cavities in the head around the nose,eyes and cheeks.atarrh is not a serious problem but it can lead to other infections of the sinuses or middle ear. The symptom is usually associated with the common cold, but can also be found in patients with middle ear infections, tonsillitis, sinusitis or an adenoid infection. Some blockages may be chronic.