What is Er Zhi Wan?

Er Zhi Wan is a Chinese herbal formula. It is also known as Two-Solstice Pill. It is listed here as a single item (one TCM formula), not as a loose mix of separate herbs.

The formula holds just two herbs. One is the fruit of glossy privet (Nu Zhen Zi). The other is the herb eclipta (Mo Han Lian, also called Han Lian Cao).

Each herb is picked at a solstice, the longest and shortest days of the year. That is where the name Two-Solstice Pill comes from.

Chinese medicine uses it for a pattern called liver and kidney yin deficiency (a dry, over-heated, worn-down state). In day-to-day terms, people take it for dizziness, ringing in the ears, a sore low back and knees, dry eyes, night sweats and early grey hair.

Here is the honest bottom line. The formula has a long record of use in China, but good human trials are almost absent. Long traditional use is not proof that something works, and that caveat applies to everything on this page.

How does Er Zhi Wan work?

No one has shown clearly how Er Zhi Wan works in the body.

The traditional idea is simple. Chinese medicine says the formula feeds yin, the cooling and moistening side of the body. When yin runs low, the body is said to run dry and hot, which is linked to night sweats, dry eyes and a sore low back.

Lab and animal work gives some hints, but no firm answer. In test tubes, both herbs act as antioxidants, meaning they mop up unstable molecules that can damage cells. Animal studies have looked at bone cells, liver cells and immune cells.

Those findings are early. They come from dishes and rodents, not people. They do not tell you what the pills will do in your body.

What forms does Er Zhi Wan come in?

Honey pills (mi wan) are the classic form. These are small, soft, dark pills.

You may also find:

Water pills or tablets, made from powdered herbs.

Capsules holding powdered herb or a dried extract.

Loose dried herbs, simmered in water at home to make a tea (a decoction).

Liquid tinctures or ready-made granules you stir into hot water.

Quality varies. Some imported herbal pills have been found to hold heavy metals or hidden drug ingredients. Buy from a seller who tests each batch and shows you the results.

Where it comes from:

Er Zhi Wan appears in Chinese formula books from the 1600s. It is most often credited to Wang Ang, who set it down in his collected formulas in 1682.

It became a staple for yin deficiency of the liver and kidney. Chinese doctors still use it today, often with other formulas rather than alone.

Its standing rests on centuries of written use in one tradition, not on modern trials.

What does Er Zhi Wan help with?

• Dizziness and lightheadedness: This is one of the main traditional uses. Chinese texts pair it with a sore low back and ringing in the ears. We found no human trial testing Er Zhi Wan for dizziness. New or sudden dizziness needs a doctor, not a herb.
• Ringing in the ears (tinnitus): A long-standing traditional use when the ringing is soft and comes with tiredness. There is no trial evidence in people for this formula. Ringing in one ear only, or with hearing loss, should be checked by a doctor.
• Sore low back and weak knees: Chinese medicine sees this as a classic sign of kidney yin deficiency, and this formula is a standard answer to it. Human proof is lacking. Back pain has many causes, so get a diagnosis first.
• Dry, tired eyes and blurred vision: Glossy privet fruit has a long record of use for the eyes in Chinese medicine. Lab work shows antioxidant activity, but that does not prove an eye benefit. No good human trial of the formula for eye symptoms was found.
• Night sweats and hot flushes: Traditionally used for heat that rises at night with a dry mouth. Some Chinese-language reports look at menopause symptoms, but they are small and weakly designed. Treat this as unproven.
• Early greying and thinning hair: Both herbs have a folk name for darkening hair, and eclipta is used this way in India too. There is no reliable human trial showing it changes hair colour or regrows hair.
• Bone thinning (osteoporosis) support: Animal work suggests glossy privet may act on bone cells. That work has not been repeated in solid human trials. Do not use it in place of bone medicine your doctor has prescribed.

Which foods are rich in Er Zhi Wan?

You cannot get this formula from your diet; it only comes as a herbal product.

What are the side effects of Er Zhi Wan?

• Loose stools or diarrhoea
• Upset stomach or nausea
• Mild belly pain or bloating
• Poor appetite
• Skin rash or itching (uncommon)
• Feeling cold or washed out in people with weak digestion

Good to know:

Most people who take it report no problems. When side effects do happen, they are usually mild and involve the gut.

The formula is seen as cooling in Chinese medicine. If your digestion is already weak and your stools are loose, it can make that worse.

Stop taking it and speak to a doctor if you get a rash, yellow skin or eyes, or dark urine. Serious harm from these two herbs has not been reported often, but product quality is a real risk. Poorly made herbal pills have been found to hold heavy metals or hidden drugs.

How much Er Zhi Wan should you take?

• Recommended daily: No dose has been set by human trials. The amounts below come from traditional and modern Chinese practice. Honey or water pills: about 6 to 9 g a day, usually split into two doses. Dried herbs simmered as a tea: about 9 to 15 g of each herb a day. Capsules and extracts: follow the label, as strengths differ widely. Start at the low end. A trained Chinese medicine practitioner will often adjust the amount or add other herbs to suit you.
• Best time of day: Usually twice a day, morning and evening. Some practitioners suggest the evening dose for night sweats. Timing is based on custom, not on study results.
• With or without food: Take it after food with warm water. This lowers the chance of an upset stomach. Pills taken on an empty stomach are more likely to cause nausea.
• Time to effect: Nothing is likely to change in the first few days. Traditional use expects gradual change over 2 to 6 weeks. There is no trial data to confirm any timeline.
• How long to take it: Traditional use is over weeks to months, not days. A fair trial is about 4 to 8 weeks. Check in with yourself at 8 weeks. If nothing has changed, stop and speak to a practitioner or doctor. Long, non-stop use for many months has not been studied for safety.