Wild asters, the daisy-like flowers that crowd fields and roadsides in late summer, have been used as medicine on more than one continent for centuries. The recurring theme is the chest: coughs, colds and congestion. Most of what science has tested, though, comes from Asian asters studied in cells and mice, not the North American plants most foragers pick. And the clearest proven issue for an everyday user is a risk rather than a benefit, since asters belong to a plant family known for causing allergies.
How North American Peoples and Herbalists Used Wild Aster
Native American peoples ate aster. The roots went into soups, and young leaves were lightly cooked as greens.1Cornell Botanic Gardens. Arrow-Leaved Aster Crushed leaves and flowers of New England aster were applied to wounds, burns and insect bites.2The Outdoor Apothecary. New England Aster Plants: Identification, Uses, and Medicinal Benefits The Ojibwa applied an infusion of aster root to ease headaches.3Cornell Botanic Gardens. Arrow-Leaved Aster The Iroquois mixed aster with bloodroot and other plants as a laxative, and parts of the flower were used for venereal diseases.4Cornell Botanic Gardens. Arrow-Leaved Aster
Modern herbalists use New England aster mostly for colds. They make a tincture, an alcohol extract, from the fresh flowering tops.5Herbal Academy. 3 Late-Summer Herbs and How to Use Them: New England Aster, Chrysanthemum, and Goldenrod As a hot tea, it is used to promote sweating during colds and flu.6Herbal Academy. 3 Late-Summer Herbs and How to Use Them: New England Aster, Chrysanthemum, and Goldenrod Herbalists say the tea and tincture together ease cough, sinus congestion and headache.7Herbal Academy. 3 Late-Summer Herbs and How to Use Them: New England Aster, Chrysanthemum, and Goldenrod Still, aster is a minor herb in Western herbal tradition, and most species are rarely used.8Herbal Academy. 3 Late-Summer Herbs and How to Use Them: New England Aster, Chrysanthemum, and Goldenrod
Traditional records tell you what a community reported using aster for, not whether it worked. Many uses were in blends, so aster’s own role is unclear. Accounts also say “aster” for several related native plants, so the species a particular people used may not be the New England aster in your field. The herbalists’ advice on tea and tincture rests on practitioner experience passed along in books, and nobody has tested it in people.
Aster in Chinese Medicine for Coughs
Tatarian aster root has been recorded in Chinese medical texts since the Han Dynasty.9PubMed Central. Radix Asteris: Traditional Usage, Phytochemistry and Pharmacology of An Important Traditional Chinese Medicine Later herbals from the 5th to 17th centuries kept listing it.10PubMed Central. Radix Asteris: Traditional Usage, Phytochemistry and Pharmacology of An Important Traditional Chinese Medicine It was used to relieve coughs and clear phlegm by “warming” the lungs.11PubMed Central. Radix Asteris: Traditional Usage, Phytochemistry and Pharmacology of An Important Traditional Chinese Medicine Tatarian aster is a different plant from New England aster, and similar use doesn’t prove the same chemistry.
If you want to buy aster root as a Chinese herb, it may be sold as “Zi Wan” or Radix Asteris. It is the root, not the flowers foragers pick, so check the species named on the label.
What Lab and Animal Studies Show
The cough claim has some animal support. In mice, a Tatarian aster extract increased the clearing of mucus from the airways and reduced how often they coughed.12PubMed. Expectorant, antitussive, anti-inflammatory activities and compositional analysis of Aster tataricus It also delayed the onset of coughing and reduced swelling.13PubMed. Expectorant, antitussive, anti-inflammatory activities and compositional analysis of Aster tataricus Compounds in the extract reduced airway inflammation, a main driver of cough and phlegm.14PubMed Central. An updated and comprehensive review of the morphology, ethnomedicinal uses, phytochemistry, and pharmacological activity of Aster tataricus L. f
Anti-inflammatory effects show up repeatedly. An extract of one Korean aster calmed gut inflammation in mice with colitis.15PubMed. Anti-inflammatory effects of an ethanol extract of Aster glehni via inhibition of NF-κB activation in mice with DSS-induced colitis Another aster extract lowered inflammatory signals in immune cells in a dish.16PubMed Central. Anti-Inflammatory Effects of Aster incisus through the Inhibition of NF-κB, MAPK, and Akt Pathways in LPS-Stimulated RAW 264.7 Macrophages Compounds from chamchwi reduced brain inflammation in mice.17PubMed Central. Astragalin and Isoquercitrin Isolated from Aster scaber Suppress LPS-Induced Neuroinflammatory Responses in Microglia and Mice18Journal of Functional Foods. Neuroprotective and anti-neuroinflammatory effects of ethanolic extract from leaves and stems of Aster glehni
Other findings are early. One aster extract killed lung and skin cancer cells in a dish,19Academic Journals. Antitumor, cytotoxic and antioxidant potential of Aster thomsonii extracts but that is a first step most candidate drugs never get past.
The one human trial was in Korea. In 12 weeks, 44 adults with obesity took 700 mg a day of an Aster spathulifolius extract and lost about 3.3 kg, versus almost none on placebo.20PubMed. Aster spathulifolius Maxim extract reduces body weight and fat mass in obese humans No side effects linked to the extract were seen, but blood sugar and cholesterol did not change.21PubMed. Aster spathulifolius Maxim extract reduces body weight and fat mass in obese humans This is one small trial of one species in pill form, not evidence for wild aster tea.
Mice got concentrated extracts dosed by body weight, far stronger than steeping leaves in water. A cup of tea holds a much smaller and unknown amount of the active compounds, and nobody has measured what a home brew delivers. Plant chemistry also shifts with where the plant grows, and work on one aster from different regions found its compounds varied.22PubMed. Comprehensive LC-MS/MS and HPLC-based profiling of secondary metabolites in Aster incisus from diverse cultivation regions
The species matter as well. Nearly all these studies used Asian asters such as Tatarian aster and Korean species, not New England aster. Botanists have moved many North American asters into other genera, so the name on a study and the name in a field guide may not match.
Allergy Risk and Other Safety Concerns
Animal tests found low toxicity. Rats given an aster extract for 13 weeks at very high doses showed no harm, and that extract did not damage DNA in standard tests.23PubMed Central. Evaluation of Subchronic Toxicity and Genotoxicity of Ethanolic Extract of Aster glehni Leaves and Stems A Tatarian aster extract was lethal only at very large doses, though long-term feeding caused scattered changes in blood and liver tests.24PubMed Central. EVALUATION OF THE ACUTE AND SUBCHRONIC TOXICITY OF Aster tataricus L. F. Animal safety tests, however, don’t capture allergic reactions in people.
Asters belong to the daisy family, which includes ragweed, chamomile and chrysanthemum. This family is a well-known cause of skin and pollen allergies.25PubMed Central. Allergic Potential of Medicinal Plants From the Asteraceae Family Certain compounds in these plants can sensitize the skin and cause rash and inflammation, and almost half of them are potential contact allergens.26PubMed Central. Asteraceae species as potential environmental factors of allergy This allergy is about as common as reactions to standard patch-test allergens, and it often becomes long-lasting.27PubMed. Compositae dermatitis: a survey Swallowing these compounds can trigger whole-body reactions in sensitized people,28PubMed Central. Allergic Potential of Medicinal Plants From the Asteraceae Family and people allergic to the family can cross-react with related foods and pollens.29PubMed Central. Asteraceae species as potential environmental factors of allergy
That makes some people poor candidates for aster. If you have ragweed hay fever, or have reacted to chamomile or echinacea, you share a plant family and have a higher chance of reacting. If daisies or chrysanthemums have given you a rash while gardening, aster could do the same to your skin. Pregnant or breastfeeding people have no safety data, so avoiding it is the sensible choice. The same goes for anyone taking prescription medicines, because interactions have not been studied.
If you decide to go ahead, start with one small, weak cup of tea and wait a full day before trying more, since allergic reactions can be delayed. Stop right away at itching, a rash, wheezing or swelling, and don’t try again. If your skin is sensitive, wear gloves when you harvest, since skin is where reactions to this family often begin. Seek urgent medical care for swelling of the throat or trouble breathing rather than waiting to see if it passes.
Harvesting and Preparing New England Aster
Harvest at peak bloom in late summer or early fall.30The Outdoor Apothecary. New England Aster Plants: Identification, Uses, and Medicinal Benefits Pick on a dry, sunny day to lower the risk of mold.31The Outdoor Apothecary. New England Aster Plants: Identification, Uses, and Medicinal Benefits Cut flower heads and leaves with clean shears, leaving stem so the plant recovers, and take no more than a third of a colony.32The Outdoor Apothecary. New England Aster Plants: Identification, Uses, and Medicinal Benefits Then hang small bundles upside down out of direct sun for 1 to 2 weeks until they crumble.33The Outdoor Apothecary. New England Aster Plants: Identification, Uses, and Medicinal Benefits Store the result in an airtight container away from light and moisture.34The Outdoor Apothecary. New England Aster Plants: Identification, Uses, and Medicinal Benefits
Where you pick matters. Avoid roadsides and sprayed lawns, because plants there can take up exhaust residues and herbicide that you would then drink. Get permission before picking on private land, and don’t pick in parks or reserves where plant collecting is not allowed.
For a first cup of tea, pour just-boiled water over a small amount of dried flowers and leaves. Cover the cup and let it steep for several minutes so the aroma stays in the drink. Strain it well through a fine strainer or cloth, since fine hairs on the plant can irritate the throat.
Telling Wild Asters Apart From Look-Alikes
Asters bloom from late summer into fall, with purple, blue or white rays around a yellow center. New England aster has hairy, clasping leaves and deep purple flowers.
Several plants can fool you. Fleabane has very thin, numerous rays and often starts blooming earlier in the season, so a daisy-like flower in early summer may well be fleabane. Ox-eye daisy has fewer, broader white rays around a yellow center, unlike the many narrow rays of an aster. Goldenrod often grows next to asters and blooms at the same time, but its flowers are small yellow plumes rather than daisy-like heads. Use a regional field guide or a plant ID app, and treat the app’s answer as a lead to confirm against a guide before you use the plant.
A plant you can’t name may carry its own toxicity, and a daisy-like flower is no guarantee of safety. If you mix species in one batch, a reaction becomes hard to trace to any one plant.