The oils should not be stored with the droppers in place as the vapors may corrode the dropper. If stored properly essential oils will keep for about 1 year. Some citrus oils, eg lemon, orange and lime will not keep for as long. Every persons sensitivity to oils can vary considerably. If you have a high sensitivity it is best to start treatment with a lower dose and work up.
Sensitivity can vary according to the herbs used.
Some herbs have a mild effect, Chamomile for example, others have a stronger effect on the system and should be treated with respect. Some herbs, whilst having a beneficial effect in most cases are inappropriate to us in others. Any herb with a stimulating effect on the uterus is inappropriate for use during pregnancy. Prolonged cumulative exposure to certain natural chemicals may also have an irritant effect upon the body. In each of the detailed descriptions of essential oils we describe the circumstances in which use of the herbs should be avoided or care taken.