Elderberry syrup for colds and flu: evidence, raw berry poisoning and safe use

Most products are made from the berries of Sambucus nigra, the black elder that grows in British hedgerows. Shop-bought syrups, gummies and lozenges use cooked or processed extract. The flowers, used for cordial, are a separate product. This page is about the berry preparations sold for coughs, colds and flu.

The NCCIH reports that some preliminary research suggests elderberry might relieve symptoms of flu, colds or other upper respiratory infections, but it stresses that only a small number of studies have looked at this. Trials differ in the preparation tested, the dose and the people enrolled, and many are small. A modest symptom benefit is therefore possible but not firmly established.

There is no evidence that elderberry prevents infection or replaces vaccination. For flu, vaccination in eligible groups remains the main prevention, and people at higher risk of complications who develop flu symptoms should speak to their GP or NHS 111 about whether antiviral treatment is appropriate.

This is the part that surprises people. Raw or unripe elderberries and other parts of the elder tree, including the leaves and stems, contain poisonous cyanide-producing substances. They can cause nausea, vomiting and severe diarrhoea, and large quantities can cause serious illness. Cooking eliminates the toxin.

If you make your own syrup from foraged berries, follow a tested recipe, use only fully ripe berries, remove stalks and leaves, and heat the fruit thoroughly. Never eat raw berries off the bush, and do not make drinks from whole stems or bark. Anyone who becomes unwell after eating raw elderberries should contact NHS 111, and call 999 if they have severe vomiting, drowsiness or confusion.

• Use fully ripe berries only and discard stalks, leaves and unripe fruit.

• Cook thoroughly before drinking or eating.

• Do not give home-made preparations to young children without checking with a pharmacist or GP.

The NCCIH page does not set out specific side effects for properly cooked berry preparations, and advises people to discuss elderberry with a healthcare provider because some herbs and medicines interact. Syrups and gummies contain sugar, which matters for people with diabetes and for children's teeth.

The NHS says to check with a pharmacist before taking a herbal medicine alongside prescribed drugs, and it lists groups such as statins, antidepressants, diabetes medicines, blood-pressure tablets, warfarin and hormonal contraceptives where interactions can occur. People taking immunosuppressants after a transplant or for an autoimmune condition should ask their specialist, because products marketed as immune boosting may be unsuitable.

During the pandemic elderberry was promoted as a protective or curative product. The NCCIH states there is no good evidence to support its use for COVID-19, and the US regulators took enforcement action against companies making unsupported claims. In the UK, advertising a food supplement as treating or preventing a disease is a breach of rules, so claims of that kind on a pack or website should be regarded as a warning.

Little is known about whether it is safe to use elderberry in pregnancy or while breastfeeding. The NHS recommends against herbal medicines in both and says they are not advised for children because safety data are lacking. A parent worried about a feverish child should use NHS 111 or a GP rather than syrup.

Most colds settle with rest, fluids and simple pain relief. Seek advice for breathlessness, chest pain, a fever that persists, confusion, a rash that does not fade under a glass, or worsening symptoms after initial improvement. Babies, older adults, pregnant women and people with long-term conditions have a lower threshold for getting help.

In the UK, most elderberry syrups and gummies are food supplements and are not assessed for effectiveness. Registered traditional herbal medicines carry a THR mark, which the MHRA grants for safety, quality and information, not proof of benefit. The MHRA has warned that most herbal products are unlicensed with variable standards.