The drinking of olive leaf tea by Middle Eastern cultures has had many uses including coughs, sore throat, cystitis and gout. Poultices were also made, using the olive leaves, to treat complaints such as boils, warts and other skin complaints.

The main constituent of the olive leaf is the phytochemical, oleuropein which is broken down to elonolic acid. This has a powerful anti bacterial effect and the ability to interfere with critical amino acid production essential for viruses. Oleuropein is a bitter monoterpene glycoside of the class known as secoiridoids and is also one of the major components found in the polyphenolic portion of olive oil. Studies have proven the effectiveness of the olive leaf extract to lower blood pressure, but this is still under investigation. It does seem to help in combating the spread of viral infections and although there is still research going on, olive leaf extract is now available in capsule form to be taken to boost the immune system and it could help against the cold and flu germs in the winter months.