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:

Oral anticoagulants

Patients who have had a venous thrombosis or embolism or a cardiac arrhythmia (especially atrial fibrillation) may require treatment with an anticoagulant and for some people treatment is lifelong. 


Historically anticoagulation has been achieved using medicines which antagonise vitamin K-dependent clotting factors (e.g. warfarin). Their use is complicated by a narrow therapeutic range, extensive drug interactions and a requirement for routine monitoring with blood tests. In overdose, an antidote, vitamin K, is available to reverse their effects. More recently, directly-acting anticoagulants (DOAC’s) have been introduced (e.g. apixaban, dabigatran, edoxaban and rivaroxaban) which do not require routine therapeutic monitoring. Not all DOACs had antidotes available, however, and concerns have been raised about consequences of overdosage. 


The pattern of anticoagulant prescribing in the UK is changing, with the use of directly acting agents becoming more common. This has resulted in increases in the numbers of NPIS telephone enquiries received about these agents (Figure  1). This year the NPIS received more telephone enquires (410) than in recent years concerning oral anticoagulants. An increase in enquiries about DOAC’s has been accompanied by a smaller fall in the number of enquiries about warfarin (Figure 2). Enquiries concerning DOACs are now more than twice as common (286) than those involving warfarin (124). Most enquiries concerned patients who were asymptomatic, but the NPIS will continue to monitor the pattern of enquiries concerning oral anticoagulants.


Figure 1. Telephone enquiries concerning individual direct oral anticoagulants




Figure 2. Telephone enquiries concerning warfarin and direct oral anticoagulants




Information from the NPIS Annual Report 2016/17.


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