What Is Henna?

Medically Reviewed by Zilpah Sheikh, MD on April 21, 2024
8 min read

Henna (also called mehndi, anella, or lalle) is a temporary “tattoo” and hair dye made from the henna plant (Lawsonia inermis). People in many cultures use it to create elaborate designs on the skin. This tradition typically celebrates joyous events like weddings, births, circumcisions, and victories. 

Although it’s often referred to as a tattoo, henna is really a temporary stain left by a plant-based paste. In very rare cases, the paste could cause an allergic reaction. Most reactions aren’t to the henna itself, but to chemical additives.

Various forms of henna span across many religions and cultures, including Hinduism, Buddhism, Sikhism, Zoroastrianism, Jainism, Judaism, Christianity, and Islam. It typically is used to bless a newly married couple with good health, fertility, wisdom, and protection from demons.

Henna has been used in Africa, the Middle East, and Asia for thousands of years. Historians believe it was discovered by shepherds, who noticed that it stained the mouths of the livestock that ate it. The desert dwellers might have quickly realized that the plant didn’t just change skin color: It also acted as a coolant. When smeared on feet or hair, henna paste cooled down that body part as it dried. Some cultures even use it to treat burns and headaches. 

Ancient Egyptians used henna to preserve mummies and dye their wrappings. They also used it to treat ringworm and other diseases. In addition, they began the practice of using henna paste as a decorative skin dye. Like many later cultures, they created temporary tattoos with intricate patterns. This is how mehndi – body art that uses henna – was first developed.

Henna plant

The henna plant is a small bush that thrives in hot environments ranging from deserts to tropical forests. It probably began in North Africa and the Middle East, then spread across Asia. Now, it grows all over the world. 

The leaves and stems of the henna plant contain a dye called lawsone. When the plant is crushed, whether fresh or dried, this copper-colored dye is released. It is then collected as a powder and mixed with water to form a paste. In some cultures, people add ingredients like lemon or lime juice, tea, or essential oils. These can make the color richer or longer-lasting. 

The dye sticks to a protein called keratin, which is found in hair, skin, and nails. Hands and feet have the most keratin, which is why the stains are darkest on those body parts. 

Henna flowers have a strong, sweet fragrance. As a result, the plant is sometimes grown in gardens or used in perfumes. 

On its own, henna makes a reddish-brown or coppery dye. Sometimes, chemicals are added to create other colors. But these added chemicals can be dangerous. When someone has an allergic reaction to henna, it is usually caused by the added chemicals and not the henna itself. 

Natural henna

Natural henna refers to henna paste that doesn’t have any added chemicals. It is also called red henna. The paste is greenish-gray and becomes orange when moistened.

Black henna

Black henna, also called blue henna, is made using chemicals like coal-tar dye. This black dye contains a chemical called p-phenylenediamine (PPD). PPD dries more quickly than natural henna. It also makes the stain darker and longer-lasting. In the United States, PPD can be used to dye hair, but not skin, eyelashes, or eyebrows.

Some people have dangerous skin reactions to PPD. One study found that a henna paste with a 10% PPD concentration caused reactions in everyone who tested it. The FDA tested 10 black henna products and found PPD concentrations ranging from 4% to 27%.

Henna is part of traditions from several cultures. It’s often used to celebrate happy occasions and share blessings. In addition, some cultures use it as a dye or medicine.

Some of these traditions include:

  • During Moroccan Jewish weddings, family elders will smear henna on the palms of the newlyweds. 
  • In West Africa, henna paste is made into thin strips that won’t stain the skin. These strips can be washed off later. It’s used for good luck, baby naming ceremonies, and other happy events.
  • In North African nomadic groups, women create tent fabric that mimics henna patterns. This symbolizes women’s ability to pass down traditions through art and reproduction.
  • Henna is also used as a clothing dye by Muslims and Jews, some of whom don’t use manmade dyes.
  • In some Arab countries, henna is used to treat boils and other conditions. 

Some popular designs include:

The hamsa. Also known as the hand of Mary, the hand of Miriam, or the hand of Fatima, this design features a hand with an eye in the palm. It is used to protect against a curse called the evil eye and to celebrate peace.

Plants. In Morocco, patterns with fruit, vines, and flowers symbolize growth. They celebrate marriage or pregnancy.

Paisley. This design, first found on 7th century silk, features repeating curved shapes. Some people think this pattern was inspired by the Indian mango.

Geometric patterns. Because West African henna is pasted on in thin strips, these designs tend to feature more straight lines and geometric designs. These lines form natural images like leaves and feathers. Repeated triangles symbolize fish scales, indicating good luck in fishing. 

Henna paste is made by grinding the stems and leaves of the henna plant. When it’s time to use it, you put the paste into a paper cone, carrot bag, or hypodermic needle. Then, you gently squeeze the cone and draw. This lets you pipe out the paste into your desired patterns. 

After 2 to 6 hours, you wash off the paste. The longer you leave it on, the darker the stain will be. The color will darken over the next 2 to 4 days.

Henna tattoos

Many cultures use henna to create temporary “tattoos.” These tattoos often feature intricate designs that symbolize prosperity and other blessings. They’re used to celebrate weddings and other joyful events. But in the U.S., the FDA hasn’t approved henna for use on skin.

Henna hair dye

You can use henna to dye your hair a rich shade of auburn. In fact, many Egyptian mummies have hair dyed with henna – and still sport red locks today!

Henna brows

Some people use henna to dye their eyebrows and eyelashes. In the United States, natural henna and black henna can be used to dye hair, but not skin, brows, or lashes.

Henna freckles

A recent beauty trend has inspired some people to paint on henna freckles. But henna is not approved for use on skin in the United States. Also, you should always be careful about applying cosmetics to your face.

Henna lip stain

In recent years, some people have started using henna to color their lips. There is little to no research about the safety of this practice.

Henna dyes the outer layer of skin, so the tattoo disappears as that layer is worn away. This is called exfoliation. It’s the natural process of old skin falling away and being replaced by new skin. It happens faster when the skin is exposed to sun or water.

You also can exfoliate with a brush, sponge, or certain creams. Be gentle: Scrubbing too hard or using a product that is too strong could damage your skin.

Black henna might be harder to remove. One study suggests dabbing the area with a cotton ball soaked in polyethylene glycol 400. This is a chemical used in drugs and cosmetics. You can buy it online. To avoid smearing, don’t rub the cotton ball. You’ll need to do this several times, rinsing frequently with water.

How long does henna last?

Henna usually lasts for a few days or weeks. It can last up to 6 weeks, depending on how much sun and water exposure it gets.

In the United States, henna is approved only as a hair dye. It is not approved for use on the skin. If it is intended for use on the skin, it cannot be imported into the country.

Like other cosmetics, store-bought henna needs to come with an ingredients list. You are not allowed to sell it across state lines. But professionals who apply henna in salons or fair booths do not need to display the ingredient list.

Some possible risks include:

Skin reactions. Natural henna is generally safe. But in rare cases, it can cause an allergic reaction. 

Most reactions are to black henna, not natural henna. Black henna contains added chemicals, like PPD, which are used to enhance the color. About 1 in 40 people who get black henna tattoos have a severe allergic reaction to PPD.

If you have a reaction to PPD, you are much more likely to have serious (and even life-threatening) allergic reactions to other types of hair dye. You may also develop allergies to:

  • Rubber and/or latex
  • Certain fabrics, including leather, fur, and nylon
  • Certain chemicals in paints, photographic developers, and inks
  • Sulfonamide antibiotics
  • Some drugs for irritable bowel syndrome
  • Other chemicals and metals

Thick hair growth. Sometimes, black henna can cause thick, rapid hair growth on that area of skin. This goes away within a few months.

Lead contamination. Researchers in Serbia, Iran, and Turkey have found lead and other heavy metals in some henna products, including hair dye. Lead, PPD, and other chemicals have also been found in black henna from Sudan and other African countries. As a result, some people have gotten poisoned and had renal failure and other problems.

Anemia. Henna can cause life-threatening anemia in children with a rare enzyme disorder called glucose-6-dehydrogenase deficiency. Signs include:

  • Pale or yellowish skin
  • Tiredness
  • Vomiting
  • Abnormal heartbeat

A true henna allergy is very rare. In fact, there have only been a few reported cases of henna allergies. The reaction can happen when the paste touches your skin, or when you accidentally breathe in henna dust.

Symptoms of a henna allergy include:

  • Sneezing
  • Irritated, pinkish eyes
  • Swelling in the face
  • Trouble breathing
  • Hives

Nearly all reactions to henna are caused by PPD found in black henna. If you’ve never used PPD before, the rash will take a week or two to develop; if you have used it before, the rash will appear in a few days.

The rash might be:

  • Red
  • Extremely itchy
  • Oozing
  • Blistering
  • Scaly

Rarely, PPD can cause hives, extra hair growth, and anaphylactic shock.

The rash is sensitive to UV rays in sunlight, so you’ll probably need to protect it with sunscreen. After it heals, you might notice changes in skin coloring and scarring.

There’s no way to tell who will have a reaction to PPD, but it’s more common in people who are allergic to:

  • Other dyes
  • Certain antimicrobials
  • Some sunscreens
  • Local anesthesia
  • Rubber and/or latex

Usually, a doctor can diagnose this allergy based on your symptoms. But sometimes, they might suggest allergy testing to confirm.

Allergies can be diagnosed with a patch test. For this test, a doctor will put a small sample of a watered-down allergen on your skin. A few days later, they’ll check the site to see if a rash has formed.

A similar option is a prick test. For this test, a doctor puts a few drops of a possible allergen on your skin and pricks it with a tiny needle. About 20 to 30 minutes later, the doctor will check to see if there’s been a reaction.

If you’ve already had an allergic reaction to henna or PPD, you might not need a test. But because a reaction to PPD can trigger other types of allergies, a proper diagnosis is important. Patch and prick tests can help the doctor figure out if you’re allergic to anything else.