Lu Hui
Do not self-treat with Lu Hui
If this is an emergency
Some reactions to Lu Hui need urgent care. Call your local emergency number or go to an emergency department straight away — do not wait to see whether it passes.
Who should avoid Lu Hui?
- Never use Lu Hui if you are pregnant. It can make the womb contract and may bring on a miscarriage.
- Do not use it if you are breastfeeding. The active chemicals pass into breast milk and can loosen a baby's stool.
- Never give it to a child under 12.
- Do not use it if you take digoxin or any other heart rhythm drug.
- Do not use it if you take water pills (diuretics) or steroid medicines such as prednisolone.
- Do not use it if you have a blocked bowel, or if you cannot pass stool or wind at all.
- Do not use it if you have belly pain that has not been explained by a doctor, or if you may have appendicitis (a swollen appendix).
- Do not use it if you have Crohn's disease or ulcerative colitis (long-term swelling and sores in the bowel).
- Do not use it if you have kidney disease or heart failure.
- Do not use it if you are dehydrated, or if you have had diarrhoea or vomiting in the past few days.
- Do not use it if you already have low potassium (a salt the heart and muscles need).
- Do not use it for longer than one week, and never as a daily habit.
- Do not use it if you have haemorrhoids (swollen veins around the back passage) that are bleeding.
- Do not use it to lose weight. It removes water, not fat, and the risks are real.
When should you see a doctor?
Stop the herb and see a doctor within a day if you get bad belly pain, you keep vomiting, or the diarrhoea does not stop. Also see a doctor if you still cannot pass stool after a week of use.
Get urgent help, the same day, if you feel very weak or dizzy, your muscles feel floppy, or your heart feels fast or uneven. These can be signs that your potassium has dropped too low.
Call emergency services if you have severe belly pain with a hard, swollen belly, if you vomit blood, or if you pass blood or black tarry stool.
Tell your doctor or pharmacist that you are taking Lu Hui, above all if you take heart drugs, water pills, steroids or warfarin.
- What it is: Lu Hui is dried bitter aloe leaf sap, used in Chinese medicine as a strong short-term laxative.
- Active ingredients: Aloin (barbaloin), Aloe-emodin, Other anthraquinones (bitter chemicals that act on the gut)
- Side effects: Cramps and loose stool are common; long use can drain potassium and affect the heart.
- Pregnancy & breastfeeding: Avoid in pregnancy and while breastfeeding.
Educational information, not medical advice — ask your doctor or midwife.
What is Lu Hui?
Lu Hui is dried aloe juice. It is the bitter yellow sap from just under the skin of aloe leaves, dried into a hard dark lump. On labels it is also called Aloe, or dried leaf concentrate.
This is a single herb, not a herb mix. Chinese medicine uses it mainly as a strong laxative, which is a medicine that makes you pass stool. Small doses were also used for what old texts call liver heat, and for worms in children.
The evidence here is thin. Aloe sap does move the bowels, and that effect is well known. But good human trials on Lu Hui itself are lacking, and long traditional use is not proof that it works.
Lu Hui is not the same thing as aloe gel. Gel is the clear jelly inside the leaf, and it is much milder. Lu Hui is the bitter outer sap, and it acts hard on the gut.
Because it acts so hard, it is meant for short use only. It can drain fluid and salts from the body.
It also clashes with several common drugs. Some people must never take it at all. The safety section below lists them.
How does Lu Hui work?
Lu Hui works mostly inside the large bowel.
It holds bitter plant chemicals called anthraquinones. The main one is aloin. Gut bacteria change aloin into an active form once it reaches the large bowel.
That active form does two things. It makes the bowel wall squeeze harder, and it pulls water into the stool. Softer stool plus harder squeezing means a bowel movement, usually within several hours.
The same action explains the cramps, the watery stool and the salt loss that can follow. Losing too much potassium, a salt the heart needs, is the reason this herb is risky with some heart and water drugs.
Old Chinese texts explain it another way. They say Lu Hui is cold and bitter, and that it drains heat downward from the liver and the gut. That is a traditional idea, not a tested one.
What forms does Lu Hui come in?
Lu Hui comes in a few forms:
Raw dried lumps or granules of hard, dark brown sap, broken up for use.
Powder, packed into capsules or pressed into pills. This is the usual way it is taken, because the taste is very bitter.
As one herb inside a classical Chinese formula, such as Dang Gui Lu Hui Wan.
As a paste or wash put on the skin or scalp in traditional practice.
It is not usually boiled as a tea. The resin does not dissolve well, and the taste is hard to swallow.
Where it comes from:
Aloe sap has a very long record. Greek, Arabic, Indian and Chinese healers all used it as a purge, going back well over a thousand years.
In China it appears under the name Lu Hui in materia medica texts from the Tang and Song periods, after arriving through trade. It was placed in the group of herbs that drain heat and move the stool.
It has stayed a standard, if strong, item in Chinese herbal practice ever since, used in short courses rather than daily.
What does Lu Hui help with?
- Short-term constipation (trouble passing stool): This is the one use with a clear, known effect. Aloin makes the bowel squeeze and pulls water into the stool, so a bowel movement usually follows. Most of the trial work was done on senna and other herbs in the same family, not on Lu Hui. So we can say the herb works as a laxative, but we cannot say how it compares with gentler options. It is for short use only. Fibre, fluid, movement and milder products are better first steps.
- Hard, dry stool with heat signs, as described in Chinese medicine: Chinese texts pick Lu Hui for hard stool with signs they call heat, such as a red face, bad breath and a dry mouth. That pattern is a traditional way of sorting symptoms. It has not been tested in trials, and it does not match any lab test. The stool-moving effect is real. The pattern theory around it is tradition.
- Worms in the gut (traditional use): Old texts used Lu Hui to help clear worms, often with other herbs. We found no human trials that back this. Modern worm medicines are safe, cheap and proven, and a stool test can tell you what you have. If you think you have worms, see a doctor rather than treat yourself.
- Poor appetite and weight loss in children, called gan ji (traditional use): Classical practice used tiny doses of Lu Hui in children who were thin and had a poor appetite. There is no modern trial support for this. Today the herb is not advised for children at all, because of fluid and salt loss. Weight loss in a child needs a doctor, not a herb.
- Anger, headache and red eyes from liver heat (traditional use): Formulas such as Dang Gui Lu Hui Wan were used for a short temper, headache, red eyes and a bitter taste in the mouth. This is tradition only. No human trials test Lu Hui for mood, headache or eye symptoms. Ongoing headaches have many causes, and some need checking.
- Itchy or flaky skin and scalp, used on the skin (traditional use): Pastes and washes made from the sap were put on the skin and scalp in several traditions. Most modern skin research uses aloe gel, the clear jelly, not this bitter sap. The two are not the same product. On the skin, the sap can sting, redden or irritate. Test a small patch first.
What are the side effects of Lu Hui?
- Belly cramps and griping pain
- Watery stool or diarrhoea
- Feeling sick (nausea)
- Loss of fluid, which can leave you dizzy or very thirsty
- Low potassium (a salt the heart and muscles need), causing weak muscles and tiredness
- An uneven or fast heartbeat, if potassium falls far enough
- Red or brown urine, which is harmless but can be a shock
- A lazy bowel and worse constipation after long use
- Contractions of the womb, which is why it is banned in pregnancy
- Stinging or redness when put on the skin
Good to know:
Cramps and loose stool are common, even at normal doses. They usually stop when you stop the herb.
The serious problems come from taking it too long or too often. Losing fluid and potassium can affect the heart, and this risk is higher if you also take water pills or heart drugs.
One more concern: in animal studies, whole leaf aloe extract that still contained aloin caused bowel tumours in rats. The International Agency for Research on Cancer lists it as possibly cancer-causing in people. This has not been shown in humans, but it is a good reason to keep use short.
Review status
This page has not been signed off by a pharmacist and is not published. It is shown here for a policy decision only.