"The best thing with which to color your gray hair is henna or katm." [Abu Daawood and At-Tirmithi]
Salmah, the Prophet's (saw), maid, said: “Anyone who complained to the Prophet from pain in his head, he would say to him, ‘cup it.’ And when complained from pain in the foot, he would tell him, ‘Dye it with henna.’” [Abu Daawood and Ibn Maajah]
She also said: “Whenever the Prophet (saw) had an ulcer, fester or eczema, he ordered me to put henna on it.” [Authentic, Jaami' al-Usool by Ibn al-Atheer]
Henna has been utilized since ancient times as a dye to color the nails, hands, feet and hair. The traditional henna is manufactured from a plant known as Lawsonia Alba. This plant is cultivated in Saudi Arabia, India, Sri Lanka, Iran, Egypt, North Africa and Australia among others.
The effective dye component of henna is called Lawsone. It consists of fat, resin, manitol and volatile oils.
It is mentioned in the Islamic Encyclopedia of Medicine that the ancient Egyptians used henna in mummification.
The Egyptian henna is typically a green substance that gives the hair a reddish brown color. Other colors are obtained by adding other dyes to the natural henna. Some women in Sudan add a substance called paraphenylen ediamine to the henna to reduce the time needed for dyeing from an hour to several minutes. But this mixture can be fatal although its cause is unknown and this is why people who apply henna are warned against adding this substance. Henna in itself is safe and doesn't have any known side effects. It is 100% natural. The henna found in different brands of shampoos in stores and pharmacies is free of this substance.
Recent medical researches:
Many people in recent years have been inclined to use natural substances. The idea of returning to using some old substances that were once used as cosmetics is gaining ground in the medical field. One of these substances is henna. If we look at the different haircare products available off-the-shelf like shampoos, conditioners, hair color and hair creams, we will find that much of them contain henna.
This substance is described in the Hadeeths as being the best source for hair dyeing. What is the scientific evidence that encourage the return to the use of henna?
An American magazine specializing in skin diseases, Cutis, once published an article about henna in its first edition in 1986. Dr. Natu is a famous professor of skin disease from New York University in America, stated that henna has several benefits, the most important being as follows:
1. Its effects are not permanent. It does not stick permanently to the roots of the hair like other artificial hair colors. Henna starts to fade after 3 to 6 weeks. It then disappears completely and leaves no residue.
2. Henna is compatible with all natural hair colors.
3. Henna enhances the natural color of hair and gives it shine. One would have to use it several times before any visible changes in color appear.
4. Henna strengthens each individual hair, restores damaged hair and prevents split ends. There are many different shampoos and conditioners that contain henna and do not give the hair any new color. They give it beauty and glow.
5. Extensive usage of henna is safe in comparison with other artificial substances. There are only rare cases of skin sensitivity.
Didn't the prophet (saw) say, “The best thing to color your hair with is henna and katam.” Recent medical evidence in our hands proves what the Prophet said. That is not strange because the Prophet said, “Henna is the best perfume for the people of Jannah.” If the henna is the preferred perfume in paradise, it is the ideal hair treatment on this earth.
via ~ islamweb