15 Herbs for Lungs and Coughs: What the Evidence Really Says

15 Herbs Promoted for Lung Health: Claims and Safety Warnings

Can herbs help your lungs? Some can ease a cough or a scratchy throat for a while, and a few have modest evidence behind them, but no herb has been shown to repair damaged lung tissue, cure a chest infection or replace treatment for asthma, COPD or pneumonia.

The fifteen plants below come from a widely shared list compiled by herbalist John Summerly for Prevent Disease. Each one has a long history in folk medicine, and several turn up in cough drops and chest rubs you can buy at any pharmacy. What follows explains what each plant is, why people use it, what research actually shows, and where the real risks lie. Four of them, licorice, coltsfoot, lobelia and chaparral, can cause serious harm, so read those entries with care.

Why herbal lung remedies need a careful look

Herbal medicine is often presented as the gentle alternative to drugs. In reality, plants contain active chemicals, and anything strong enough to change how your body works is strong enough to cause side effects. Aspirin came from willow bark and digoxin from foxglove; both are useful and both can be dangerous at the wrong dose.

Three points are worth keeping in mind before trying any remedy on this list:

A test-tube result is not a treatment. Many claims rest on lab studies in which a purified compound killed bacteria or slowed cancer cells in a dish. That tells us little about a cup of tea.
Traditional use explains interest, not effect. A plant used for centuries may still do nothing measurable, or it may help one symptom and harm the liver.
Infections differ. Most coughs and colds are viral, and antibiotics do not work against viruses at all, as the CDC explains. Bacterial pneumonia, by contrast, can be life-threatening and needs proper medical care.

Earlier versions of this list also claimed that medicines kill about a million Americans a year while herbs kill nobody. Neither figure has a reliable source. Herbal products do cause poisonings and liver injuries, and regulators in several countries have pulled some of them from sale.

Soothing herbs for coughs and sore throats

15 Plants and Herbs That Can Boost Lung Health, Heal Respiratory Infections And Even Repair Pulmonary Damage

These are the gentlest plants on the list. Most are kitchen herbs or common weeds, and their main value is comfort: warm steam, a coated throat, a pleasant taste that makes you drink more fluids.

1. Thyme

Thyme leaves contain thymol, an aromatic oil that kills microbes in laboratory tests. Thyme has been a cough remedy in Europe since antiquity, and the European Medicines Agency's herbal committee accepts it as a traditional herbal medicine for productive coughs linked to colds. That is a recognition of long, safe use rather than proof of strong effect. A cup of thyme tea with honey is a reasonable home comfort for adults.

2. Sage

Garden sage has been gargled for sore throats for centuries. Its oils include camphor and thujone, which explains the strong scent. Steam from sage tea may feel soothing, but large amounts of sage oil should not be swallowed, because thujone can trigger seizures in high doses.

3. Peppermint

Peppermint's key ingredient is menthol, which triggers cold-sensing nerves in the nose and throat. That is why a menthol lozenge makes breathing feel easier even though measurements show it barely changes airflow. Chest rubs and lozenges with menthol are fine for most adults; concentrated peppermint oil should never be put near the face of a baby or small child.

4. Eucalyptus

Eucalyptus trees are native to Australia, where Aboriginal people used the leaves long before Europeans arrived. The main active compound, cineole (also called eucalyptol), is found in many lozenges, rubs and steam inhalers. Small trials suggest cineole capsules can reduce flare-ups in some people with chronic bronchitis, but pure eucalyptus oil is toxic when swallowed, and a few millilitres have poisoned children.

5. Oregano

Oregano oil contains carvacrol, which damages bacteria, including Staphylococcus aureus, in laboratory dishes. Claims that it beats antibiotics come from those lab studies, not from trials in people. Cooking with oregano is harmless; swallowing concentrated oil can irritate the stomach and mouth.

6. Plantain leaf

This is not the banana-like fruit. Greater plantain (Plantago major) is a flat-leaved weed found on lawns and paths almost everywhere, and it is not related to the plantain banana. Its leaves were used as poultices for cuts and stings, and the related ribwort plantain is a traditional cough syrup ingredient in Europe. Evidence in people is limited.

Traditional mucus-clearing herbs

The next group comes from Western and Native American herbalism, where they were used as expectorants, meaning remedies meant to loosen phlegm. None has strong clinical evidence, but most are low risk when used sensibly.

7. Mullein

Mullein is the tall, woolly-leaved plant that grows along roadsides in Europe and North America. Herbalists make tea from the leaves and flowers for coughs. If you try it, strain the tea through a fine cloth: the tiny leaf hairs can irritate the throat, which is the opposite of what you want.

8. Elecampane

Elecampane (Inula helenium) is a large yellow-flowered plant native to Europe and Asia, later grown in North American gardens. Its root contains inulin and bitter compounds and has been used in European cough syrups for centuries. Human studies are scarce, and people allergic to ragweed or daisies may react to it.

9. Osha root

Osha (Ligusticum porteri) grows high in the Rocky Mountains and was valued by several Native American nations for colds and respiratory complaints. There are almost no clinical studies on it. It is also slow-growing and hard to cultivate, so conservation groups worry about over-harvesting; if you buy it, look for responsibly sourced material. It closely resembles poison hemlock, so never pick it yourself.

10. Lungwort

The name covers two different things. Tree lungwort (Lobaria pulmonaria) is a lichen whose lobed surface looks a little like lung tissue, and that resemblance is why it was prescribed for lung disease under the old "doctrine of signatures." Garden lungwort (Pulmonaria) is a flowering plant with spotted leaves that got its name the same way. A shape is not evidence, and neither has been shown to help lungs in proper trials.

11. Cannabis

The original list praised vaporised cannabis as a way to open airways and even reverse asthma. That claim is not supported. The American Lung Association warns that smoking cannabis damages the lungs and can cause chronic bronchitis, and says little is known about the safety of vaping it. Cannabis compounds have shown anti-cancer effects in lab and animal studies, but that research has not produced a lung treatment.

Four herbs with serious safety warnings

These plants appear in many lung-health lists, yet each has a documented record of harm. Do not take them without a doctor's advice, and never give them to children or use them during pregnancy.

12. Licorice root

Licorice is a staple of Chinese herbal formulas and a pleasant, sweet throat soother. The problem is glycyrrhizin, its main sweet compound. In larger or regular doses it makes the body hold on to salt and lose potassium, which can raise blood pressure and disturb heart rhythm. The US National Center for Complementary and Integrative Health says there is not enough good evidence for licorice in any condition and warns that large amounts are unsafe in pregnancy. People with high blood pressure, heart or kidney disease, or who take diuretics or heart medicines should avoid it. Deglycyrrhizinated licorice (DGL) has the risky compound removed.

13. Coltsfoot

Coltsfoot (Tussilago farfara) gets its Latin name from tussis, cough, and has been used in Europe for that purpose for a very long time. It is native to Europe and Asia and was carried to the Americas by settlers, so the popular claim that Native Americans used it for thousands of years does not fit its history. It contains pyrrolizidine alkaloids, which can damage the liver and caused tumours in animal studies. Germany banned its sale, and growers later bred an alkaloid-free variety for the herbal trade.

14. Lobelia

Lobelia (Lobelia inflata), also called Indian tobacco or puke weed, is native to eastern North America and was once smoked for asthma. Its main alkaloid, lobeline, acts somewhat like nicotine. The nickname is a warning: lobelia readily causes nausea and vomiting, and larger amounts can lead to a racing heart, tremors, convulsions and even death. It is not a safe home remedy.

15. Chaparral

Chaparral comes from the creosote bush (Larrea tridentata) of the deserts of the US Southwest and northern Mexico, where Indigenous peoples used it for wounds, cramps and other ailments. In the 1990s it was linked to serious liver injury, including at least one case that required a liver transplant. The FDA has warned against taking it internally, and Health Canada told consumers in 2005 to avoid it because of liver and kidney damage. The fact that a compound in chaparral, NDGA, slows cancer cells in the lab does not make the herb safe to drink.

Common myths about herbs and lung health

"Natural means safe." Coltsfoot, lobelia and chaparral are as natural as thyme, and they have injured people. Dose, preparation and your own health all matter.

"Herbs are ignored only because they can't be patented." Companies cannot patent a plant, but they can and do patent extracts and formulations, and herbal supplements are a large, profitable industry. Researchers study herbs regularly; many simply fail to outperform a placebo.

"Herbs can detox or repair the lungs." Healthy lungs clear themselves with mucus and tiny hair-like cilia. The best-proven way to help that system is to stop smoking, avoid smoke and polluted air, and stay active. Damage from long-term smoking or disease is not reversed by tea.

Using herbs sensibly

Stick to culinary herbs in food-like amounts (thyme, sage, peppermint, oregano) if you want a comforting home remedy.
Tell your doctor or pharmacist about every herb and supplement you take, because some interact with blood pressure drugs, blood thinners and heart medicines.
Buy from reputable sellers. Herbal products are not tested like medicines, and contamination or mislabelling happens.
Do not give herbal oils or strong teas to babies, young children or anyone pregnant or breastfeeding without medical advice.
See a doctor promptly if you have shortness of breath, chest pain, a high fever, blood in your phlegm, or a cough lasting more than three weeks. If you have asthma or COPD, keep using the treatment you were prescribed and talk to a doctor before adding anything.

Herbs can be part of looking after yourself when you have a cold. They work best as small comforts alongside rest, fluids and good medical care, not as a replacement for it.

Sources: Original list by John Summerly, Prevent Disease; CDC: Antibiotic use; NCCIH: Licorice root; MSD Manual: Licorice; American Lung Association: Marijuana and lung health; Wikipedia: Coltsfoot; Wikipedia: Lobelia inflata; Wikipedia: Larrea tridentata; UChicago Medicine: Herbal medication linked to liver failure; Wikipedia: Lobaria pulmonaria; Wikipedia: Plantago major.

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