May cause skin irritation through repeated use, especially if used undiluted or in highly concentrated form. Avoid in early pregnancy if there's a history of miscarriage. Those who suffer with hay fever or asthma may be allergic.

France

One of the most popular oils with a multitude of uses.

Added to bathwater:
Soothing tension and headaches, relieving stress and lifting depression.
In a vaporiser/burner:
Nervous system disorders, such as anxiety and insomnia and also shock, vertigo, hypertension and migraine.
One to two drops of the neat, or diluted, oil rubbed into the skin or applied as a compress:
Acne, boils, sores, spots, psoriasis, bruises, burns (including sunburn), dermatitis, eczema, athlete's foot, ringworm, scabies, insect bites and stings. It can also be used as insect repellent.
Massage (diluted in a carrier oil):
Easing digestive symptoms such as colic, flatulence, abdominal cramps and indigestion, menstrual pain, cystitis, aches and pains, and stimulating circulation.
A few drops added to shampoo:
Treating dandruff and warding off head lice.
Steam inhalation:
Easing coughs, colds and congestion.
1 drop on a sugar cube (caution, use only unadulterated oil):
Nausea, travel sickness

NB: there's more than one type of lavender oil. Spike lavender (Lavandula latifolia) has a more stimulating scent and is most effective for respiratory problems.