A bacteriostatic is any substance which inhibits the growth of bacteria. It may not destroy bacteria, but will halt the growth of the organisms so that they do not present a threat to health.

The human body can deal efficiently with the many different bacteria that it encounters at every moment of each day, and it is only when a particular strain of bacteria begin to multiply rapidly that the body's defences may not be adequate, so restricting the spread of bacteria is a valuable aspect of preventive medicine.

All essential oils of plants are bacteriostatic to a greater or lesser degree. Some are effective against a limited group of bacteria, and others against a very wide range, and the amount of essential oil needed to produce a bacteriostatic effect is very small indeed. Among the most effective oils for this purpose are Clove, Garlic, Lavender, Sage and Thyme, and indeed all the herbs which have been traditionally used in cooking have this property, even in very low concentrations