Ding Xiang

Seventy-three adult volunteers had homemade clove gel, benzocaine 20 percent gel, or matched placebos applied to maxillary canine buccal mucosa for five minutes in randomised, subject-blinded fashion, then received two needle sticks scored on a 100 mm visual analogue scale. Both clove and benzocaine gels gave significantly lower mean pain scores than their placebos (p = 0.005), with no significant difference between clove and benzocaine. This is the best human evidence for the classical topical use of the drug for toothache.

Randomised double-blinded placebo-controlled crossover in sixteen male social drinkers taking a single 250 mg capsule daily of a standardised clove bud polyphenol extract or placebo, with alcohol dosed at 1 g/kg/day and a two-week washout before crossover. The extract accelerated blood acetaldehyde elimination and significantly lowered oxidative stress, lipid peroxidation, C-reactive protein and interleukin-6 while raising glutathione and superoxide dismutase, with hangover severity reduced by 55.34 percent. Small and industry-flavoured, but it is a genuine crossover RCT of the bud, and importantly it tested the polyphenol fraction rather than the essential oil.

Fourteen head and neck cancer patients were randomised to a clove-based herbal mouthwash or clear water during radiotherapy. The mouthwash shortened the duration of grade 2 or worse mucositis (24.3 versus 37.1 days, p = 0.044) and reduced weight loss during treatment (3.1 versus 7.4 percent, p = 0.023), with non-significant reductions in grade 3 mucositis, feeding-tube use and radiotherapy interruption. Fourteen patients is a pilot, and the mouthwash was a multi-herb preparation rather than clove alone, so this supports rather than establishes the indication.

A randomised triple-blind trial of clove mouthwash for oral care in mechanically ventilated intensive care patients, with ventilator-associated pneumonia incidence as the endpoint. It is the largest and most rigorously blinded clove trial available and, like the mucositis study, tests topical oral use rather than the systemic indications the drug is prescribed for in Chinese medicine.

In human platelets, eugenol at 2 microM inhibited collagen- and arachidonic-acid-induced aggregation while leaving thrombin- and U46619-induced aggregation unaffected, and suppressed ATP release, P-selectin expression, intracellular calcium, PLCgamma2/PKC, PI3K/Akt/GSK-3beta, MAPK signalling and cPLA2/thromboxane A2 formation. In ADP-treated mice it reduced platelet occlusion of lung vessels without prolonging bleeding time. This is the mechanistic basis for treating clove as a mild antiplatelet agent, and the unchanged bleeding time is the reason not to overstate the bleeding risk.

Case report with literature review. A three-month-old girl ingested less than 8 mL of clove oil, was decontaminated and admitted, then developed fulminant hepatic failure. She was given intravenous N-acetylcysteine on the protocol used for paracetamol poisoning, and her hepatic synthetic function and clinical state improved over 72 hours to full recovery. The review of earlier clove oil toxicity cases makes this the reference point for the drug's principal serious hazard.

A seven-month-old developed central nervous system depression, urinary abnormalities and a large anion-gap metabolic acidosis after accidental oral administration of clove oil, and recovered fully on supportive care and gastric lavage. The earliest of the clove oil paediatric poisoning reports, and evidence that the toxicity is not confined to the liver.

A further paediatric clove oil ingestion managed with early N-acetylcysteine, reinforcing both the hazard and the antidotal approach carried over from paracetamol poisoning. Recent enough to show that these exposures are still occurring where clove oil is kept in the home.