Rehmannia: Benefits, Uses & Dosage

Some herbs cross borders. Rehmannia (Rehmannia glutinosa), called Di Huang in Chinese medicine, is one that Ayurvedic practitioners have borrowed and described in their own terms, because it does something they value: it cools and it rebuilds at the same time.

In Chinese medicine it is an important tonic and rejuvenative for the kidneys and liver, used to counter ageing and dryness. It is not a classical Ayurvedic herb, so you will not find it in the Charaka Samhita, but its Ayurvedic profile is clear. It tastes sweet and bitter, has a cooling potency (Sheeta Virya), and a sweet post-digestive effect (Madhura Vipaka), meaning its effect after digestion is nourishing.

The root comes in two forms. The raw root is cooling and is used to clear deep-seated fevers. The cooked root (Shu Di Huang) is slightly warming and is the form used for most tonic purposes.

Rehmannia calms Pitta and Vata. Its heavy, nourishing nature means it can aggravate Kapha and undigested residue (Ama), which is the main thing to know before you try it.

Rehmannia's benefits come from one combination: it is cooling enough to calm Pitta, and nourishing enough to rebuild depleted tissue. Ayurvedic practitioners describe it as Kapha-like in nature, meaning it increases the body's tissues, fluids and secretions. Its listed actions are nutritive tonic, rejuvenative (Rasayana, a herb that renews tissue), aphrodisiac, demulcent (soothing to membranes), laxative and emmenagogue (promotes menstruation).

Blood and anemia

Both raw and cooked Rehmannia decrease Pitta and are used for Pitta disorders such as anemia. It acts on the plasma (Rasa Dhatu) and blood (Rakta Dhatu), the two tissues involved in making blood, and it is described as a tonic for the liver.

Hair loss

Hair loss is on Rehmannia's list of indications. Its cooling action suits thinning linked to heat, and its nourishing side suits hair that is dry and depleted, especially with age.

Kidneys, low back and ageing

Rehmannia is indicated for weak kidneys, low back pain and senility. It reaches the deeper marrow and nerve tissue (Majja Dhatu), which is why it fits the depletion that comes with ageing.

Reproductive health

It acts on the reproductive tissue and is indicated for sexual debility in men and women and for irregular menstruation. Cooked Rehmannia is described as a good substitute for Shatavari as a tonic and rejuvenative for the uterus.

Diabetes and the liver

Rehmannia is also listed for diabetes and cirrhosis. Our sources give no further detail on these uses, and both conditions need medical management, so treat them as reasons to talk to a practitioner rather than to self-treat.

Rehmannia root is taken internally, prepared as a decoction (a simmered tea) or as a powder. The first decision is which form of the root you want.

Raw or cooked?

For most people looking for a tonic, the cooked root is the usual choice. The raw root is more strongly cooling and is used mainly for fevers, which is a job for a practitioner.

Working with your digestion

Rehmannia is heavy. If your digestion is sluggish, a small dose is the safer start, and if digestion is genuinely weak it is not the right herb. Our sources give no specific vehicle (Anupana, what you take a herb with) or seasonal guidance.

Give it time

As a rejuvenative tonic, Rehmannia works gradually. Think in months of steady use, not days.

Rehmannia is a nourishing tonic, and its main risks come from that same heaviness. The listed precautions are short and specific.

Who should avoid it

• Weak digestion. Its heavy, nourishing nature can overwhelm a weak digestive fire and build undigested residue (Ama).
• Severe congestion. It increases fluids and secretions and can aggravate Kapha.
• Edema. Fluid retention is a listed precaution, for the same reason.

Laxative effect

Rehmannia is listed as laxative. Looser stools are a sign the dose is too high or the herb does not suit you.

Menstruation and pregnancy

It is described as an emmenagogue, meaning it promotes menstruation. That is a reason for caution in pregnancy; see the populations section below.

What our sources do not cover

Our sources list no drug interactions or overdose signs. If you take regular medication, particularly for diabetes or liver disease, speak to your doctor before adding Rehmannia.

Rehmannia is usually compared with the Ayurvedic herbs that do a similar job. Here is how it stacks up, based on what our sources say.

Our sources give limited population-specific guidance for Rehmannia. Where they are silent, the safest course is to consult a qualified practitioner before use.

Pregnancy & Nursing

Rehmannia is described as an emmenagogue, a herb that promotes menstruation. That is a reason to avoid it in pregnancy unless a qualified practitioner prescribes it. Our sources give no guidance for nursing, so ask first.

Children

There is no guidance on Rehmannia for children in our sources, and no child dose. Do not give it to children without professional advice.

Elderly

This is where Rehmannia is most at home. It is indicated for senility, weak kidneys and low back pain, and it reaches the deeper marrow and nerve tissue. Older digestion is often weaker, though, and weak digestion is a listed precaution, so start at the low end of the range.

Athletes

Our sources describe no specific use for athletes. Its nourishing, tissue-building nature is general, so there is no particular reason to seek it out for sport.