Threadworm ( Pinworm ) Infections in Primary Care - Treating

Publication: 30/09/2010  
Next review: 21/10/2023  
Clinical Guideline
ID: 2253 
Approved By: LAPC 
Copyright© Leeds Teaching Hospitals NHS Trust 2020  


This Clinical Guideline is intended for use by healthcare professionals within Leeds unless otherwise stated.
For healthcare professionals in other trusts, please ensure that you consult relevant local and national guidance.

Treating Threadworm (Pinworm) infections in Primary Care

Treat all household contacts at the same time (even if not symptomatic)
advise hygiene measures for at least 2 weeks
wash sleepwear, bed linen, dust, and vacuum on day one and repeat regularly 1C

 Preferred Option

Alternative Option


All patients over 6 months of age*:


100mg  single dose 1C (off-label if <2yrs) plus hygiene measures.

Dose may be repeated in 2 weeks if infestation persists.




< 6 months of age: Use hygiene measures alone for 6 weeks 1C






Pregnant - use hygiene measures alone for 6 weeks

Hygiene measures: Follow for 2 weeks if combined with drug treatment or for 6 weeks if used alone:

  • Wear close-fitting underpants or knickers at night. Change them every morning.
  • Cotton gloves may help prevent night-time scratching. Wash them daily.
  • Bath or shower immediately on rising each morning, washing around the anus to remove any eggs laid by the worms during the night.
  • For children < 6 months use perianal wet wiping or washing every 3 hours during day.

General personal hygiene measures — encourage all the time for all household members:

  • Wash hands and scrub under the nails first thing in the morning, after using the toilet or changing nappies, and before eating or preparing food.
  • Discourage nail biting and finger sucking.
  • Keep nails short
  • Avoid the use of 'communal' or shared towels or flannels.

NICE CKS Threadworm

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General Principles for Treating Infections

This guidance is based on the best available evidence but its application must be modified by professional judgement.

  1. A dose and duration of treatment is suggested. In severe or recurrent cases consider a larger dose or longer course
  2. Choices are given as Preferred option or Alternative for patients intolerant of the preferred option and 2nd Line for when an alternative is required because of treatment failure
  3. Only send microbiology specimens if there is a clinical suspicion of infection. Inappropriate specimens (e.g. routine ulcer swab or routine catheter specimen of urine) lead to inappropriate antibiotic prescribing.
  4. Prescribe an antibiotic only when there is likely to be a clear clinical benefit.
  5. Consider a no, or delayed, antibiotic strategy for acute self-limiting upper respiratory tract infections 1,A+
  6. Limit prescribing over the telephone to exceptional cases.
  7. Use simple generic antibiotics if possible. Avoid broad spectrum antibiotics (e.g. co-amoxiclav, quinolones and cephalosporins) when narrow spectrum antibiotics remain effective, as they increase risk of Clostridium difficile, MRSA and resistant UTI's.
  8. Avoid widespread use of topical antibiotics (especially those agents also available as systemic preparations).
  9. In pregnancy, take specimens to inform treatment, use this guidance alternative or seek expert advice. Penicillins, cephalosporins and erythromycin are not associated with increased risks. If possible, avoid tetracyclines, quinolones, aminoglycosides, azithromycin, clarithromycin, high dose metronidazole (2g stat) unless the benefits outweigh the risks. Short-term use of nitrofurantoin is not expected to cause foetal problems (theoretical risk of neonatal haemolysis). Trimethoprim is also unlikely to cause problems unless poor dietary folate intake, or taking another folate antagonist.
  10. We recommend clarithromycin as it has less side-effects than erythromycin, greater compliance as twice rather than four times daily & generic medicines are similar cost. Use erythromycin in pregnancy.
  11. Where a ‘best guess’ therapy has failed or special circumstances exist, microbiological advice can be obtained from LTHT Microbiology (Mon-Fri 9am-5pm and Sat and Sun 9am-1pm: 0113 39 23962/28580; Otherwise via LTHT switchboard - ask for the On call Microbiology Registrar)


Note: Doses are oral and for adults unless otherwise stated. Please refer to BNF for further information.
Letters indicate strength of evidence:
A+ = systematic review: D = expert opinion

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Record: 2253
Clinical condition:

Threadworm Infection

Target patient group:
Target professional group(s): Primary Care Doctors
Adapted from:

Management of Infection guidance for primary care for consultation and local adaptation

Evidence base

Grading of guidance recommendations
The strength of each recommendation is qualified by a letter in parenthesis.

Study design

Recommendation grade

Good recent systematic review and meta-analysis of studies


One or more rigorous studies; randomised controlled trials


One or more prospective studies


One or more retrospective studies


Non-analytic studies, eg case reports or case series


Formal combination of expert opinion



1. CKS (2011) Threadworm. Clinical Knowledge Summaries.!scenario Accessed 05.01.15.
RATIONALE: there is no good trial evidence regarding the efficacy of anthelmintics in the treatment of threadworm. The limited data available are from relatively old, small studies comparing mebendazole with either placebo, or with drugs that are not available in the UK. There are few contraindications to the use of mebendazole, and the manufacturer reports that post-marketing surveillance has revealed no serious safety concerns [ABPI Medicines Compendium, 2005; BNF 65, 2013]. The British National Formulary for Children recommends mebendazole for treating threadworm infection in children over 6 months; however, it is not licensed for use in children less than 2 years of age [BNF 65, 2013]. Mebendazole does not kill eggs, therefore adequate personal and environmental hygiene is essential to prevent reinfestation from recently swallowed eggs, or eggs already in the environment. The recommendation to treat people who cannot take or do not wish to take an anthelmintic with physical removal of the eggs combined with strict hygiene measures is based on expert opinion [Ibarra, 2001]. CKS found no published studies regarding the efficacy of these methods. It is based on the life cycle of the threadworm (adults survive for about 6 weeks) and the long viability of eggs (up to 2 weeks). Washing or wiping at 3 hourly intervals is intended to prevent retroinfection [Ibarra, 2001]. However washing or wiping this frequently may be impractical, and the role that retroinfection plays in reinfestation is likely to be minimal. Therefore washing or wiping twice a day may be more realistic. Piperazine, an alternative anthelmintic indicated for the eradication of threadworm in adults and children aged over 3 months, was discontinued by the manufacturer in 2012.

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Document history

LHP version 1.0

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