Many of these causes are outside the direct control of either the Welsh Government or the UK Government, which is responsible for maintaining the continuity of supply of medicines to the UK.
Mae llawer o'r rhesymau hyn y tu hwnt i reolaeth uniongyrchol naill ai Llywodraeth Cymru neu Lywodraeth y DU, sy'n gyfrifol am sicrhau parhad cyflenwad meddyginiaethau i'r DU.