Andrographis for colds and chest infections: what the evidence shows

Most colds clear without treatment, which is exactly why a herb that is said to shorten them is appealing. Andrographis is bitter, traditionally used for fevers and infections in several Asian medical systems, and is now sold in Western health shops as a cold remedy, sometimes in combination with other herbs such as eleuthero.

The pitch is usually "natural immune support". That phrase is marketing rather than a medical claim a regulator has tested, and it is worth separating from what trials really measured: patient-scored symptoms such as sore throat, cough, nasal congestion and tiredness over a few days.

A systematic review published in 2004 in Planta Medica looked for double-blind controlled trials and found seven that met its criteria, covering 896 people. All of them scored at least three out of five on a standard quality scale. Taken together they suggested that andrographis was better than placebo at easing the subjective symptoms of an uncomplicated upper respiratory infection, and there was a preliminary suggestion that it might help prevent infections.

A second 2004 review in the Journal of Clinical Pharmacy and Therapeutics reached a similar view from four studies, noting that the extract on its own, or combined with another herb, might be more effective than placebo. Its authors described the herb as a possible alternative treatment for uncomplicated infection rather than a proven one.

• Both reviews are now over two decades old, and the underlying trials were short.

• Most outcomes were self-reported symptom scores, which are vulnerable to placebo effects in a self-limiting illness.

• Different studies used different extracts and combinations, so a result for one product does not transfer to another.

• None of this addresses pneumonia, bronchitis that needs antibiotics, or flu in a high-risk person.

The 2004 safety review gathered published trials, manufacturer information and spontaneous reports held by drug safety bodies. It found that adverse events were generally mild and infrequent, and that there were few spontaneous reports. That is reassuring but limited: spontaneous reporting for herbal products is known to be sparse, a point the MHRA itself makes when it explains why Yellow Card reports of herbal reactions are low.

Practical cautions follow from general herbal-safety principles. A person with a known allergy to the plant family should avoid it. Anyone on regular prescription medicines should ask a pharmacist before adding any herb, because the NHS lists blood thinners, diabetes drugs, statins, antidepressants and hormonal contraception among the medicines that herbal products can interfere with. The NHS also says herbal medicines are not recommended for children and should be avoided in pregnancy, breastfeeding and kidney or liver problems.

In Great Britain a manufactured herbal product normally falls into one of two regulatory groups. If it is sold with a medicinal purpose such as relieving cold symptoms, it should hold a traditional herbal registration or a product licence. The MHRA grants a THR only for minor conditions that do not need medical supervision, on the basis of safety, quality and evidence of traditional use rather than proof that it works.

The same plant may also be sold as a food supplement, in which case it should not carry medicinal claims. The MHRA states that herbal or natural ingredients do not exclude a product from being treated as a medicine, and it looks at claims, ingredients and presentation, including websites and social media, when it decides. If a supplement label talks about treating colds or infections, that is a flag worth noticing.

Any herb for a cold is only appropriate while the illness behaves like one. Seek advice from NHS 111 or a GP for a high temperature that does not settle, breathlessness, chest pain, coughing up blood, a stiff neck with light sensitivity, or symptoms that continue to worsen after about a week. Call 999 for severe breathing difficulty, confusion or collapse. A herb does not replace a clinical assessment, and delaying it for a herbal trial can matter in people with asthma, COPD, heart disease or weakened immunity.

Look for a THR number on the box if it is being sold as a cold remedy, and read the patient leaflet that must accompany a registered product. Tell your pharmacist what else you take. Stop it and seek advice if you develop a rash, swelling, wheeze or any new symptom. Report suspected reactions through the Yellow Card scheme, giving the brand, ingredients and batch details, as the MHRA asks, so that patterns can be detected.