• Digestive problems
• Eczema
• Headaches
• Insomnia
• Stress.

Using essential oils
Essential oils are extracted from plant material using steam or water distillation. Selected plant materials are heated with steam, water or both until the essential oil vaporises. The oil then condenses as it cools.

All volatile aromatic plant oils are concentrated plant oils. They should be used sparingly: only a few drops at a time and always diluted in some other medium, such as plain massage oil (cold pressed vegetable oil) or unscented base cream (but not a mineral oil cream such as most brands of sorbolene or baby oil). Aromatic plant oils do not dissolve in water unless mixed with a dispersant first.

Some of the ways in which aromatic plant oils can be used include:

• Massage – 4–6 drops added to 20ml (a tablespoon) of vegetable-based oil.
• Oil burner – 6 drops added to water and vaporised in a burner. Never leave a candle oil burner unattended, as it is a fire risk. Electric vaporisers are available and are safer to use when asleep or near children.
• Bath – 4–6 drops added to a vegetable-based oil in a full bath.
• Inhalation – 2–3 drops added to a basin of hot water.

Aromatic plant oils, including essential oils, should never be ingested (taken in by mouth) as they can be toxic.

The sense of smell
The nostrils open up inside the skull to form the nasal cavity, which sits directly beneath the brain. Embedded in the ceiling of the nasal cavity are the olfactory cells. Each cell has tiny, moist hairs that trap odour molecules. It is thought that an odour is translated into electrical impulses by these cells, then passed on to the brain via the two olfactory bulbs. The message is interpreted by a part of the brain called the cerebral cortex. The sense of smell is poorly understood, but we do know that it is linked to the oldest, most primitive part of our brain and seems to have a direct link to our emotions.

Change is triggered in the brain
According to aromatherapy theory, the aromatic plant oil molecules bring about changes in the brain. Some researchers believe that when people experience mood changes or physical changes, it is because the smell has triggered a memory. For instance, if a person feels relaxed when they smell cinnamon, it might be because cinnamon conjures up pleasant childhood memories.

Popular aromatic plant oils
A few of the popular aromatic plant oils and their uses for the following symptoms include:

• Peppermint – digestive disorders.
• Rosemary – muscular pains, mental stimulant.
• Sandalwood – depression, anxiety and nervous tension.
• Sweet orange – depression and anxiety.
• Tea tree – respiratory problems, antifungal, antibacterial and antiviral.
• Lavender – headaches, insomnia, burns, aches and pains.

Handle with care
Some aromatic plant oils are toxic and should never be used at all – for example, camphor, pennyroyal and wintergreen.

Aromatic plant oils are very potent and should never be swallowed or applied undiluted to the skin. People with asthma and those prone to nose bleeds should use caution when inhaling vaporising oils. Do not use aromatic plant oils in any orifice such as ears, mouth or vagina.

Aromatic plant oils (essential oils) can be poisonous if taken in by mouth. Consumption of essential oils is an increasing cause of poisoning in children. All aromatic plant oils should be secured and kept out of reach of children. If poisoning occurs, ring triple zero (000) or the Victorian Poisons Information Centre on 131 126.

Pregnant women and people with certain conditions, including epilepsy and high blood pressure, should consult a qualified aromatherapist before using any aromatic plant oils. Some oils can be dangerous during pregnancy and for people with certain conditions.

Some people may be sensitive to aromatic plant oils
Undiluted aromatic plant oils used over sensitive areas, such as nostrils or on sensitive skin, could irritate or burn the skin. In some cases, there may be an allergic reaction such as a skin rash in susceptible people. Some of the oils that may cause problems include:

• Eucalyptus
• Ginger (carbon dioxide extracted)
• Thyme
• Black pepper
• Cinnamon
• Clove
• Oregano
• Lemongrass
• Basil
• Some citrus oils.