There are three major ways that essential oils can enter the body: ingestion, inhalation, and absorption through the skin.

Inhalation or access through the nasal passages is the quickest method for the entry of essential oils in the treatment of mental/emotional problems such as depression, stress, and certain types of headaches. The nose has direct connection to the brain which triggers the effects of the essential oils. This is not dependent on the particular route used to get there. The role of the nose is to modify the temperature and humidity of the inhaled air and filter out any foreign materials that may be inhaled.

When a person inhales a vapor, some of the molecules will travel down to the lungs where they can be of immediate positive benefit for various breathing problems. As they travel to the lungs, some molecules are absorbed by the mucous linings of the respiratory pathways and are transferred to the blood that circulates the lungs. Deep breathing enhances the amount of oils taken into the body by inhalation. It is rare to have negative effects from essential oils taken into the body in this manner.

There are many techniques and implements for the inhalation of essential oils; each is effective for the appropriate condition:

1. Tissues - inhalation from a tissue with 5-6 drops of essential oil (three for children, the elderly and pregnant women) is effective for immediate results and requires 2-3 good deep breaths. For even more effectiveness, the tissue may be placed inside the shirt or pajamas so the benefits of the oil may be extended as the body's natural heat causes the oil molecules to evaporate and travel up to the nose.

2. Q-tips - a Q-tip uses less oil than a tissue, and it is all concentrated in one small spot. Hold the Q-tip against the dropper and allow one drop to wet it. While it cannot be held up against the skin as a tissue, a Q-tip has the advantage of slower evaporation so the person can use it longer.

3. Hands - this method is excellent for adults and emergencies. It should not be used for children, however. One drop of essential oil is put onto one palm of the patient and then rubbed against the other palm. The hands are then cupped and placed over the nose with the eyes kept closed (the eye area is avoided). The patient then takes a deep, nasal inhale. Respiratory or stress conditions are often helped by this method of inhalation.

4. Steamers - it can be hazardous to allow patients to hold a basin of hot scalding water because of the possibility of it spilling, getting knocked over, or splashed onto someone, therefore, most experts recommend dry inhalation unless a proprietary brand of diffuser is available. Nebulizers are less risky although certain oils can attack the plastic and damage the equipment. Facial steamers are frequently used along with nebulizers for treating the common cold and respiratory problems. Steam - when used - quickens the relief that is obtained because the heat of the water causes the molecules to evaporate more quickly, thereby increasing the strength of the vapor and necessitating a lower amount of essential oil drops. When using steam, the following precautionary measures are suggested: a) be sure the patient's eyes are protected and observe for an adverse reaction (i.e. choking or coughing) which is more likely to occur if the dosage is stronger or too deep of a breath is taken, and b) one drop only - this is enough for asthmatics; try to keep the water at an appropriate temperature (not too high)

5. Baths - put oils into a bath for effective treatment. The oils come into contact with the skin in a gentle manner and also are simultaneously inhaled resulting in a double benefit.

6. Spray bottles - this is effective to freshen the air for patients with bed sores, gangrene, etc. Dilute 10-12 drops of essential oil in 250 mL of water. Shake the bottle carefully before diffusing into the air. Suggested oils to use: pinus sylvestris (scots pine), thymus vulgaris (thyme), syzygium aromaticum (clove), eucalyptus smithii (gully ash), and mentha piperita (peppermint).

7. Vaporizers and diffusers - in many healthcare settings today, vaporizers are the most preferred manner of using inhalation. This method releases the lightest molecules from the oil first and progressively releasing the heavier ones. Electric vaporizers are considered the only ones that are safe for health facility usage. These should be thermostatically controlled at a low temperature to prevent the essential oil from getting over-heated and too quickly used up and/or producing an unpleasant smell. Diffusers are more efficient since they push out all the oil molecules at the same time, so there is no burning or residue as with vaporizers. The disadvantage of a diffuser is cost, since the oil molecules are used up fairly rapidly, and the price of a diffuser is generally several times more than an electric vaporizer.