What is Gum plant?

Gum plant is a sticky, yellow-flowered herb from the dry parts of western North America. The dried flower tops and leaves are used in teas, tinctures and cough syrups. Grindelia robusta is the species most often sold.

It gets its name from the gummy resin on its buds. That same resin is why people call it tar weed. Herbalists have used it mainly for chesty coughs and for itchy skin rashes.

Here is the honest verdict. Long traditional use is not proof that a remedy works, and it is not proof that it is safe. Gum plant has almost no modern human evidence behind it, so treat it as tradition, not treatment.

How does Gum plant work?

No study has shown how gum plant works in a person, or that it works at all. What follows comes from lab work and from old doctors' reports.

The sticky resin holds bitter diterpene acids. In test tubes and in animals, Grindelia extracts relax smooth muscle, the muscle layer that lines the airways. Whether that eases a cough in a person is not established.

In lab tests the extracts also slow the growth of some bacteria. Some cell work points to a mild damping of inflammation (swelling and irritation). These are cell and animal findings only.

Eclectic doctors believed the resin thinned thick mucus and calmed airway spasm. They also thought the resin soothed skin after contact with poison ivy. Those ideas were never tested the way drugs are tested now.

What forms does Gum plant come in?

Gum plant is sold mostly as a liquid extract or tincture. Dried flower tops and leaves are also sold loose for tea.

You may find it in herbal cough syrups and chest blends. Capsules of powdered herb exist but are less common.

Some skin creams and washes include it for itchy rashes. Quality varies widely between brands.

Labels do not always name the exact species. Grindelia camporum and Grindelia squarrosa are sometimes sold under the same common names.

Where it comes from:

Gum plant was a staple of the Eclectic doctors in the United States in the late 1800s. They took it up from settler and Native American practice in California and the plains.

It was listed in the United States Pharmacopoeia from 1882 and later in the National Formulary. Doctors of that era gave it for asthma, bronchitis and whooping cough.

It was also applied to the skin after contact with poison ivy and poison oak. Its use faded once inhalers, antibiotics and steroid creams arrived.

What does Gum plant help with?

• Chesty cough with thick mucus: This is the main traditional use, and the evidence for it is weak. Eclectic doctors used gum plant to loosen thick phlegm. Germany's Commission E, an expert panel, later allowed it for catarrh (mucus) of the upper airways. That ruling rested on tradition and plausibility. There are no good controlled trials in people. It may help you, and it may do nothing.
• Bronchitis (inflamed airways): Traditional use is strong here. Human proof is absent. Old texts describe gum plant syrups for lingering chest infections. Lab work shows the extract can relax smooth muscle and slow some bacteria. That has not been tested in people with bronchitis. See a doctor if a cough lasts more than three weeks, or if you cough up blood.
• Wheeze and asthma symptoms: Do not use gum plant in place of asthma medicine. That is the key point on this page. Eclectic doctors gave it for asthma before inhalers existed. Animal work suggests Grindelia extracts can relax airway muscle. No trial has shown it opens airways in a person. Asthma attacks can kill, and delaying your inhaler or steroid is dangerous.
• Poison ivy and poison oak rash: A long-standing folk use, with no modern trial behind it. Frontier and Eclectic practice painted the resin onto the rash. The claim was that it dried weeping skin and stopped the itch. No controlled study has tested this. Gum plant is in the daisy family, so it can itself cause a rash in some people.
• Whooping cough (historical use only): This one is history, not advice. Nineteenth-century doctors used gum plant for whooping cough. They had little else to offer at the time. Whooping cough is now prevented by vaccine and treated with antibiotics. It is dangerous in babies. Seek medical care, not a herb.

What are the side effects of Gum plant?

• Nausea or stomach upset
• Bitter, tarry aftertaste
• Diarrhoea, mostly with larger amounts
• Skin rash or itch, in people allergic to the daisy family
• Kidney irritation, reported with large or long use
• A drop in blood pressure or a slow pulse, reported with very large amounts

Good to know:

At the small amounts on labels, side effects are usually mild and settle when you stop. Stomach upset is the most common complaint.

The serious reports involve large doses. Older medical texts describe kidney irritation and a slowed heartbeat at high intake.

Allergy is a real risk if you react to ragweed, daisies, marigolds or chrysanthemums. Stop at once if you get a rash, swelling or trouble breathing.

How much Gum plant should you take?

• Recommended daily: Gum plant is not a high-hazard herb, but it is not well studied either. The amounts below are what labels carry. They are not a dose for you. Tincture labels often list 1 to 2 mL, up to three times a day. Dried herb labels often list 1 to 2 g, brewed as a tea, up to three times a day. Products differ a lot in strength and in species. Read the label on the product in your hand. Ask a pharmacist or doctor before you start, above all if you take any daily medicine.
• Best time of day: Time of day does not matter much. People who use it for a cough often take it when the cough is worst, which for many is at night.
• With or without food: Taking it with food or a little water is kinder on the stomach. The resin is bitter and can cause nausea on an empty stomach.
• Time to effect: There is no reliable timeline, because the effect itself is not proven. If gum plant helps your cough, people who use it describe a loosening feeling within hours to a day or two. That is reported experience, not trial data. It may also do nothing at all. If nothing changes in a week, it is not working for you.
• How long to take it: Traditional use was short-term, for a cough that was already on its way out. A week or two is the usual pattern described in old texts and on modern labels. Long daily use is a poor idea. The plant can take up selenium from soil, and large or long doses have been linked to kidney irritation. If your cough is no better after a week, stop and get it looked at.