National Poisons Information Service

A service commissioned by Public Health England




Members of the public

seeking specific

information on poisons

should contact:


In England and Wales:

NHS 111 - dial 111


In Scotland:

NHS 24 - dial 111


In N Ireland:

Contact your local GP or

pharmacist during

normal hours; click here

(www.gpoutofhours for GP

services Out-of-Hours.


In Republic of Ireland:

01 809 2166



professionals seeking

poisons information

should consult:

Snake bite

The common adder, Vipera berus, is the only native venomous snake found in the UK. Its bite is uncommon but may result in serious toxicity, with an estimated 50 to 100 cases each year, with 30-50% showing marked signs of envenoming requiring treatment with an antivenom. Since 2014, a Welsh-made antivenom called ViperaTAb has been used for moderate-severe V. berus envenoming across the UK.


For the last two years, the NPIS has been auditing all cases of adder bite reported to the service that potentially required antivenom. One consultant follows up calls, speaking to the clinicians caring for the patient, advising on management of these uncommon cases and learning about the use of this antivenom.


Over the last two adder seasons (typically March/April to September, when the snakes have left their winter burrows), 61 patients were identified as requiring antivenom. Cases had a predominantly coastal region distribution with geographical clusters in the North West and South Wales, East Anglia, and Dorset. The median age of patients was 38 years with a modest male excess. Fourteen children, six aged between three and four years, received antivenom.


All patients presented with localized swelling of the affected limb while 12 also showed signs of general venom effects such as vomiting, swollen lips and tongue or low blood pressure. Most patients arrived in hospital within two hours, but a few delayed their presentation and nine cases presented to hospital more than 12 hours after the bite. Four arrived too late to receive the antivenom that would have helped them if they had got to hospital earlier.


Forty-eight (79%) patients received a single dose of antivenom while 13 needed one or two additional doses due to signs of continuing venom effects. There were only three reported mild adverse reactions amongst the 76 administered doses of antivenom. The median length of stay was a little under two days for both adults and children; a few adults remained in hospital for up to eight days due to widespread bruising and swelling of their limbs.


The audit suggested that administration of antivenom occurred soon after presentation to hospital, but a few patients did not appreciate the urgency required and did not present to hospital quickly enough. A press release was therefore published in July 2017, encouraging people to attend hospital as soon as possible after a bite so that they would gain the greatest benefit from the antivenom. It was reported widely in national print media and radio. The effects of this press release are currently being monitored. The audit also indicated that the clinicians caring for the patients appreciated the opportunity to discuss the care of these uncommon patients with an NPIS consultant, likely producing benefits for patients.






Information from the NPIS Annual Report 2017/18.


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