What are the end products of anaerobic respiration?

Anaerobic respiration occurs in the absence of oxygen. In animal cells, the end product of anaerobic respiration is lactic acid. In yeasts, the end product of anaerobic respiration is ethanol (ethyl alcohol). 

Glucose is broken down into pyruvic acid inside the cell cytoplasm. If oxygen is not available, the pyruvic acid gets converted into lactic acid, carbon dioxide and water in muscle cells. In yeast cells, the same process produces ethanol as an end product. Both end products, ethanol and lactic acid, can be toxic if they accumulate in large quantities. To prevent this from happening, cells typically switch back to aerobic respiration when oxygen becomes available.