What is Sumach?

Sumach is the bark, root bark and red berry cluster of Rhus glabra, a shrub native to North America. Folk and Eclectic healers used it as an astringent, a drying, puckering remedy for sore throats, mouth sores and loose bowels.

The ripe berries are tart and hairy with acid. They were soaked in cool water to make a tangy pink drink. The bark and root bark were simmered into gargles and skin washes.

It is also called smooth sumach, upland sumach and Pennsylvania sumach. It is not the same plant as the red cooking spice sold as sumac, which is usually Rhus coriaria.

Here is the honest verdict. There are no good human trials of Rhus glabra for any health use. Its traditional standing is long and well recorded, but tradition is not proof that it works or that it is safe.

How does Sumach work?

The proposed action is astringent. Tannins bind to proteins in the surface layer of tissue, which can make a raw throat or gum feel tighter and less weepy.

That binding is well shown in test tubes. Whether it eases a real sore throat or shortens diarrhoea in people has not been tested properly.

In laboratory tests, Rhus glabra extracts slow the growth of some bacteria and mop up free radicals. These are dish studies. They do not show that drinking a sumach tea does the same thing in your body.

Some animal and cell work on related sumach species points to effects on blood sugar and blood fats. That work is early, it is mostly not on Rhus glabra, and it should not be read as a result in people.

What forms does Sumach come in?

Sumach is sold and used in a few plain forms.

- Dried berry clusters, steeped in cool or cold water as a tart drink.

- Loose dried bark or root bark for a simmered tea, often used as a gargle.

- Liquid extracts and tinctures, a legacy of Eclectic pharmacy.

- Powdered bark, sometimes found in old mouthwash and tooth powder recipes.

For comparison, the red kitchen spice labelled sumac is a different species, Rhus coriaria. Reading the Latin name on the label is the only reliable check.

Where it comes from:

Several Native American nations used smooth sumach long before settlers recorded it. Reported uses included berry drinks for fever and thirst, bark washes for sores, and root preparations for mouth and throat complaints.

Nineteenth-century Eclectic doctors took it up. King's American Dispensatory listed Rhus glabra as an astringent for sore throat, spongy gums, mouth ulcers and chronic looseness of the bowels.

It was also used as a gargle after scarlet fever and as a wash for old wounds. These were the accepted practices of the day, written down before controlled trials existed.

The remedy faded from medical use in the early twentieth century. It survives today mainly as a foraged drink and a folk gargle.

What does Sumach help with?

• Sore throat (as a gargle): This was the best known Eclectic use. A bark tea was gargled to tighten and soothe a raw throat. No trial has tested this in people. Tannins do bind surface proteins in test tubes, which could explain the puckering feel. A gargle will not treat a bacterial throat infection. If you have a high fever, pus on the tonsils or a throat that worsens, see a doctor.
• Sore gums and mouth ulcers: Folk and Eclectic writers used sumach bark in mouthwashes and tooth powders for spongy, bleeding gums. Evidence in people is absent. Astringent rinses in general can make gums feel firmer, but that is not the same as treating gum disease. Bleeding gums often mean plaque or a vitamin problem. A dentist can tell you which.
• Mild diarrhoea: Tannin-rich plants were standard folk remedies for loose bowels, and sumach bark was one of them. There are no human trials of Rhus glabra for diarrhoea. The idea rests on the drying action of tannins, which is lab-level reasoning. Fluids and salts matter far more. Diarrhoea with blood, high fever, or lasting more than two days needs medical care, not a herb.
• Thirst and fever drinks: The cold berry infusion was a refreshing, sharp drink used in hot weather and during fevers. It is pleasant and it supplies fluid. There is no evidence it lowers a fever or shortens an illness. Treat it as a drink, not a treatment.
• Minor skin sores and washes: Bark decoctions were applied as a wash to old sores and chafed skin. Lab tests show some antibacterial activity in sumach extracts. Whether that happens on human skin is not established. Do not put plant washes on deep wounds, burns or anything that looks infected.

Which foods are rich in Sumach?

Rhus glabra berries are eaten as a tart drink rather than a food. The red spice sold as sumac in shops is usually a different species, Rhus coriaria.

What are the side effects of Sumach?

• Nausea or stomach upset, mainly from strong bark teas
• Constipation
• A dry, puckered mouth
• Reduced iron absorption with regular use
• Skin rash or itching in people sensitive to this plant family
• Mouth or lip irritation from the acid berry coating

Good to know:

Most reported problems are mild and come from the gut. They are linked to tannin content, so strong bark and root preparations are the usual culprits.

Serious reactions are rare but real. Allergic rash and swelling can occur in people who react to cashew, mango, pistachio or poison ivy, which are in the same plant family.

The bigger hazard is picking the wrong plant. Poison sumac, Toxicodendron vernix, has white or cream berries and causes a severe blistering rash.

How much Sumach should you take?

• Recommended daily: There is no established dose for Rhus glabra. No trial has set a safe or effective amount in people, so this page gives none as a personal instruction. What labels and old texts carry varies widely. Berry preparations are usually sold as a drink rather than a measured supplement. Bark products, when sold at all, tend to be liquid extracts with the maker's own serving on the label. Strong bark and root teas carry much more tannin than the berry drink. A high tannin load can upset the stomach and block iron uptake. If you are considering it, ask a pharmacist or doctor first, especially if you take regular medicines.
• Best time of day: Timing does not matter much. A gargle is used when the throat is sore. The berry drink is taken whenever you want it. There is one timing point worth knowing. Keep tannin-rich drinks away from iron tablets and iron-rich meals, by a couple of hours.
• With or without food: Food helps. Tannins on an empty stomach are a common cause of nausea. Taking it with a meal reduces that risk. The trade-off is that it may cut how much iron you absorb from that meal.
• Time to effect: If a gargle helps, the tight, soothed feeling comes within minutes and fades fast. For anything swallowed, no reliable time can be given, because the effect itself is not proven. It may do nothing at all for your symptom. That is a real possibility, not a formality.
• How long to take it: Short use only is the sensible frame. Astringent gargles and teas were traditionally used for days, not months. No study has checked what long-term daily use does. Regular heavy tannin intake is linked with poorer iron absorption. If a symptom has not settled within a few days, stop and get it looked at.