Phenomenon of Optically Enhanced Hydrogenation previously reported for 6H-SiC was now studied in the 4H-SiC polytype. Reduction of the relative intensity of Al bound exciton photoluminescence (PL) after hydrogenation followed by additional strong non-metastable quenching of this luminescence under above-band-gap light at low temperatures has been observed. More prolonged hydrogenation caused appearance of additional features in the PL spectrum. In addition to the well known H-1 line due to hydrogen-vacancy complex, a line similar to 4B(0) line previously associated with the recombination of a bound exciton at the neutral boron acceptor appeared after longer hydrogenation. Our 4B(0) PL line exhibited complex metastable quenching under optical excitation somewhat similar to the metastable quenching of H-1 line. Differences in the thermal annealing behavior of different hydrogen-related PL lines are investigated.