Thyme is a strong oil which has been shown to be a powerful germicide, being effective against many types of bacteria, fungi and viruses. It is highly stimulating for the circulatory system, and also strengthens the immune system. It may be used as a general support during convalescence. Some types of Thyme oil can be irritating to the skin. Like Rosemary, Thyme oil exhibits a number of different chemotypes. These are variations in the chemical makeup of the identical plant's essential oil as a result of different climatic factors and growing conditions. Because they have different effects, it is important to classify the oils accordingly. There are also different species of Thyme which give with different effects. The main chemotypes of Thyme are: geraniol, linalol, thuyanol, and thymol. The geraniol chemotype is mild, but has a strong anti-viral action. The linalol type is very gentle and non-irritant, suitable for use with children, and for skin care. The thuyanol type supports the liver, and is stimulating having a broad action; while the the thymol type is the most skin irritant and should therefore not be used on the skin, but is good if used in vapourisers or diffusers.