Educational information, not medical advice — ask your doctor or midwife.
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.
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.
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.
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.
Stop gum plant and see a doctor if you get a new rash, swelling, or any trouble breathing.
Get urgent care for swelling of the lips, tongue or throat. Get urgent care for a wheeze that your inhaler will not settle.
See a doctor, and stop using the herb, if any of these apply:
Your cough lasts longer than three weeks. You cough up blood. You have a fever, chest pain or shortness of breath.
Also see a doctor if you pass much less urine than usual, or get pain in your side or lower back. A poison ivy rash that spreads, blisters badly or reaches your eyes or face needs medical care too.
In the United States, gum plant is sold as a dietary supplement. It is not approved as a drug there, and products cannot claim to treat disease.
In Germany, Commission E issued a positive monograph for catarrh (mucus) of the upper airways. In the UK and EU it is sold as a traditional herbal product rather than a licensed medicine.
Evidence grades and traditional-use labels are explained in our methodology. Nothing here is medical advice.
What it is typically used for, usual dose, cautions, and the study behind it where real trial data exists.
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