What is Onkyungtang?

Onkyungtang is a Korean herbal drink made by boiling herbs in water. The name means "warm the menses" (warm the monthly period). Women take it for painful, late, or missing periods.

It is not a single herb. It is a blend of about twelve plants plus e-gyo, a glue made from donkey hide. The usual mix holds evodia, cinnamon twig, dang gui, peony, ginger, ginseng and licorice root.

It has been used in Korea, China and Japan for a very long time. Long use is not proof that a remedy works. Human trials are few and small, so we cannot say how well it works or who it helps.

How does Onkyungtang work?

The honest answer is that no one knows for sure.

In Korean medicine, the blend is said to warm a "cold" womb and get stuck blood moving again. That is an old way of thinking about the body, not a lab finding.

Lab work hints at a few ways it might act. Some plant parts ease cramping muscle. Others may thin the blood a little or shift levels of sex hormones.

Most of that work was done in dishes or in mice. We do not know if the same thing happens in a woman's body.

What forms does Onkyungtang come in?

The classic form is a tea made by boiling the raw herbs in water. One day's worth of herbs is boiled once, then split into two or three cups.

You can also buy granules, powder, pills or a ready-made bottled liquid. Granules are made by drying a strong tea into small grains, then mixing them with hot water.

Quality varies a lot between makers. Pick a brand that tests each batch for heavy metals and hidden drugs. Make sure any pinellia (banha) in the mix has been processed, because the raw root burns the mouth and throat.

Where it comes from:

The recipe is old. It first appears in the Jingui Yaolue, a Chinese medical text from around 200 CE.

Korean doctors took it up and have kept it in use for hundreds of years. It also spread to Japan, where it is known as unkeito.

Today it is still one of the better known women's health blends in East Asia. That standing rests on custom and doctor reports, not on large trials.

What does Onkyungtang help with?

• Painful periods (period cramps): This is the oldest and most common use. Korean and Japanese doctors give it to women whose cramps ease with a hot pack. Good human trials are lacking, so we cannot say how much it helps, or whether it beats a simple painkiller.
• Late, irregular or missing periods: Traditional texts point to this use first. Small reports from Japan describe more regular cycles after a few months of use. These reports had no placebo group, so we cannot rule out chance or normal change over time.
• Trouble getting pregnant linked to poor ovulation: Some Japanese clinics have used the same formula (unkeito) for women who do not release an egg each month. The published work is small and mostly open-label, meaning everyone knew what they were taking. This is not a proven fertility treatment, and it should never replace a fertility check-up.
• Hot flushes and night sweats around menopause: The formula is often given for hot flushes with dryness. Evidence here is thin and mostly from small, poorly controlled studies. If flushes are wrecking your sleep, talk to a doctor about options with real evidence behind them.
• Light spotting between periods: Tradition uses it for light, drawn-out bleeding. There is no trial evidence for this. Bleeding between periods always needs a medical check first, since it can point to something that needs treatment.

Which foods are rich in Onkyungtang?

1. Ginger: a kitchen spice that is also one of the herbs in this blend
2. Cinnamon: the bark is a food spice, while the blend uses the thin twig
3. Licorice root: sold as a sweet and a tea, and the same part that raises blood pressure

Practical Tips:

Onkyungtang is a made-up herbal blend, not a nutrient, so no food contains it. Keep licorice sweets and teas low while you take it.

What are the side effects of Onkyungtang?

• Upset stomach, nausea or loose stools
• Heartburn or a burning throat
• Headache
• Dry mouth
• Skin rash or itching
• Puffy ankles, hands or face
• Raised blood pressure
• Low potassium, which can cause muscle weakness, cramps or an odd heartbeat
• Heavier than usual period bleeding
• Rare liver injury, with yellow skin or eyes, dark urine and deep tiredness

Good to know:

Most reported problems are mild stomach upset that settles when you stop.

The two that matter most are the licorice effects (puffiness, high blood pressure, low potassium) and rare liver injury linked to evodia. Both are more likely with daily use over many weeks.

Stop taking it and get medical help if your skin or eyes turn yellow, your urine turns dark, or you feel weak and dizzy with an odd heartbeat.

How much Onkyungtang should you take?

• Recommended daily: No dose has been set by good human trials. In Korean practice, one day's tea is usually made from roughly 30 to 60 g of dried herbs, boiled down and split into two or three cups. Granule and powder products commonly give 5 to 7.5 g a day, split into two or three doses. Follow the maker's label or your practitioner's instructions, and do not double up.
• Best time of day: Usually split into two or three doses spread through the day, often morning and evening. Some practitioners start it in the week before a period is due.
• With or without food: Often taken between meals, on a fairly empty stomach. If it makes you feel sick or burns, take it with food instead.
• Time to effect: Nothing is fast. Traditional use expects a change over one to three monthly cycles, if any change comes at all.
• How long to take it: Most practitioners use it across two or three monthly cycles, then look at whether anything has changed. If nothing has changed after three cycles, stop and get advice. Long runs without a break are a bad idea, because the licorice in the mix can slowly push up blood pressure and drop potassium (a salt your muscles and heart need).