Lemon balm (Melissa officinalis) for stress, sleep and bloating

Lemon balm is a lemon-scented member of the mint family that grows easily in UK gardens. Its leaves are steeped as a calming tea, and it is often combined with valerian, hops or passionflower in sleep and "stress" blends. The convenience of picking it from a pot encourages the impression that it cannot do harm, but a cup of home-grown tea and a standardised extract in a capsule are different exposures.

The EU herbal committee describes the herbal substance as the dried or comminuted leaf, from which extracts and tinctures can be prepared, and notes that products are usually available as tea or as solid and liquid forms taken by mouth. Combination products are assessed separately.

The Committee on Herbal Medicinal Products concluded that, on the basis of long-standing use, melissa leaf can be used for relief of mild symptoms of stress and as an aid to sleep, as well as for mild digestive disorders including bloating and flatulence. It should only be used in adults and children over 12, and a doctor should be consulted if symptoms persist following two weeks of treatment.

This is a "traditional use" conclusion. It means that, although there is insufficient evidence from clinical trials, the effectiveness is plausible and the herb has been used safely in these ways for at least 30 years, including at least 15 years within the EU, for conditions that do not need medical supervision. The committee considered a small published study on mild to moderate anxiety and sleep disturbance in which a possible improvement was observed, but design shortcomings prevented firm conclusions.

• Mild and short-lived symptoms only; persistent problems need assessment.

• Two weeks is the review point in the EU monograph.

• No upper-age or pregnancy dosing is implied by a traditional-use monograph; follow each product leaflet.

The committee recorded that, at the time of assessment, no side effects had been reported with these medicines. A small randomised study published in 2015 in PLoS One gave a single dose of a lemon balm extract containing 500 mg rosmarinic acid to eleven healthy volunteers, in fasted and fed states. Rosmarinic acid peaked in blood about an hour after dosing in the fasted state, food increased exposure and delayed absorption, no effect on liver, kidney or blood cell function parameters was seen, and no adverse events were reported.

That is useful reassurance for short-term use at that dose, but it does not address long-term use, other doses, people with existing disease or interactions. Lemon balm may add to the effect of other sedatives, so people taking sleeping tablets, anti-anxiety drugs or alcohol should be cautious about combining it, and anyone driving should check how they feel first. The NHS advises asking a pharmacist before using herbal medicines with prescribed drugs, avoiding them in pregnancy and breastfeeding unless advised, and not giving them to young children.

A cup of lemon balm tea in the evening is a low-risk wind-down ritual for many adults, and the ritual itself, with caffeine cut back and screens off, probably contributes. If low mood, worry or poor sleep lasts weeks, interferes with work or relationships, or comes with panic attacks, weight change or hopelessness, speak to a GP; NHS Talking Therapies can be self-referred in England, and CBT-based insomnia programmes are recommended in preference to long-term sleeping tablets.

Seek urgent help (NHS 111, or 999 in an emergency) for thoughts of ending your life. For digestive symptoms, see a GP promptly for blood in stools, black stools, persistent vomiting, unexplained weight loss, difficulty swallowing or symptoms that wake you at night, rather than treating them with herbal wind remedies.

A traditional herbal registration shows that the MHRA assessed a product for safety, quality and patient information, and allows only minor indications based on traditional use, which fits lemon balm's profile. Teas and many capsules are sold as foods or food supplements and should not make medical claims. If a label talks about treating anxiety, insomnia or digestive disease, the MHRA may consider the product a medicine, because it examines claims, ingredients and presentation, including websites and social media.

Check for the species name, plant part, batch number and manufacturer, and read the leaflet if one is supplied. Report suspected reactions to the Yellow Card scheme with the product details.