The skin is our largest elimination organ – it both excretes and absorbs and so for some people who have particularly sensitive skin – or find that their skin is more sensitive at different times of their menstrual cycle or when they are pregnant - ordinary deodorants and antiperspirants can have an irritating effect, which is often caused by the fragrance and preservative chemicals used.

One chemical that has received a bad press over recent years is aluminium and its compounds, which are used to inhibit sweating. Some people think that that by stopping the sweat, toxins build up in the body and this could be linked to the development of breast cancer. No research has yet proved this.

Sweat is odourless; it is only when it reacts with bacteria on the skin that smells arise. Deodorants kill bacteria and leave a pleasant smell. Antiperspirants prevent sweating. Skin irritation can occur if these products are used on already irritated skin, right after shaving, or spread too widely around the armpit.

For people who may have concerns about aluminium or who have sensitive skin, natural deodorants are the answer and these are becoming more widely available. These are based on alum which inhibits the bacteria but is not absorbed by the skin.