Elderflower has been used in traditional medicine all over the world for its antiseptic and anti-inflammatory properties.
The most common uses are for colds and flu, sinus infections, and other respiratory disturbances. As a supplement, elderflower also has diuretic and laxative properties and is helpful in relieving occasional constipation.
Elderflower has antibacterial and antiviral properties and may also help alleviate some allergies and boost the functioning of the immune system. Topically, elderflower might help reduce pain and swelling in joints due to some forms of arthritis and is used to stop bleeding.
As an oral rinse, elderflower can be used for its antiseptic properties as a mouthwash and gargle. For toothache, this infusion should be held in the mouth for a few minutes. Elderflower water is a pleasant bath additive and lotion for the skin and eyes.
I used boiling water and steeped for five minutes, adapt this advice to suit your personal preferences. It does make for a wonderful comforting drink.
It goes without saying that if you're pregnant (or are under the doc for anything) caution should be exercised with herbal decoctions.