Species of Achillea contain alkaloids for defending themselves against insects and herbivores.
The fresh plants can therefore be hung in a room while still aromatic to repel insects.
Herbivores, however, have developed foraging strategies to avoid the toxic alkaloids: donkeys, which are attracted to sharp smelling plants, nibble off the flowers, while camels avoid it until late in the season when foraging gets more difficult and then feed off the dead leaves at the bottom.
The volatile oils show broad antimicrobial action and are used as an antiseptic for urinary tract infections and as a treatment for diarrhoea or colic. Cooled infusions can also be applied to purulent sores or used as eye-drops against eye infections.
The oils have muscle relaxant properties and are used for chest pains, cough and muscular rheumatism, and it is given to women after childbirth to help them rest and relax. For a sprained ankle, bathing the foot in warm water infused with qaysoum will ease the pain and promote healing.
Infusions can also be drunk to relieve headaches and nausea.
Qaysoum flowers between March and October, though flowers can still be found in December or January. It has a strong smell and bitter taste and for this reason it is usually infused with sugar when drunk, though for digestive problems it is best to avoid the sugar and endure the bitterness. Water is boiled and then removed from the heat before adding the leaves. Excessive heating will drive off the aromatic oils.
 Donkeys are attracted to Achillea fragrantissima, Artemisia judaica, Asteriscus graveolens, Peganum harmala, Salvia lanigera and Varthemla iphionoides. Clinton Bailey, Avinoam Danin, 1981, Bedouin plant utilization in Sinai and the Negev, Economic Botany, Vol 35
 Ali M. Al-Gaby, Univ of Cairo, 2000, Chemical Analysis, Antimicrobial Activity, and the Essential Oils from Some Wild Herbs in Egypt, Journal of Herbs, Spices and Medicinal Plants, Vol 7,
 MUSTAFA E. H., Univ of Jordon 1995, Effects of cirsiliol, a flavone isolated from Achillea fragrantissima, on rat isolated smooth muscle, International journal of pharmacognosy Vol 33