Varicella Zoster ( Chicken Pox ) Infection in Adults - Guideline for management

Publication: 01/08/2008  
Next review: 16/06/2025  
Clinical Guideline
ID: 1465 
Approved By: Improving Antimicrobial Prescribing Group 
Copyright© Leeds Teaching Hospitals NHS Trust 2022  


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.



For patients with a presumed diagnosis of varicella zoster virus (VZV) (chicken pox) the following diagnostic tests should be taken to confirm diagnosis:

Chickenpox is usually a relatively straightforward clinical diagnosis, however, disseminated herpes simplex, enterovirus or mycoplasma infections may produce similar rashes. Laboratory confirmation is not usually required other than for these atypical cases.

Atypical cases

In cases where there is doubt regarding the diagnosis, then a swab of vesicular fluid can be taken for HSV, VZV and enterovirus PCR:

  • Using the viral swab, remove the top from a lesion and swab. This swab should then be placed in the clear liquid medium provided.
  • If a viral swab is not available, then a standard wound swab can be used, but the tip should be cut off and placed in a dry white topped sterile universal container.

PCR is a sensitive and specific test for VZV. It is useful for old or crusted lesions but is expensive and takes at least 1 day to obtain a result. In cases where encephalitis or meningitis is suspected, PCR can also be performed on CSF.
Testing blood for the presence of VZV IgG antibodies is not helpful in diagnosing chickenpox and should not be performed. It is primarily used to determine immune status in specific populations (e.g. healthcare workers).

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  • Paracetamol is effective in relieving mild to moderate pain and pyrexia
  • Ibuprofen and other NSAIDs should be avoided
  • Chlorphenamine may relieve itch and reduce sleeplessness
  • Topical calamine lotion (obtained from stores) may be useful for itchy rash

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Patients with primary varicella zoster virus (chickenpox) should be placed in an isolation room/suite and health care workers should wear a fluid resistant surgical facemask for routine care and FFP3/hood for aerosol generating procedures whilst the patient is considered infectious i.e. until lesions have crusted over. Please refer to IPC guidelines for further information.

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  • Doses assume normal renal function (see BNF for advice in renal impairment)
  • Note in obese patients, ideal body weight should be used when calculating the dose of intravenous aciclovir

Empirical options for Varicella (chicken pox)

Referral criteria

  • All immunocompromised patients should be referred to infectious diseases
  • Immunocompetent adults with complicated chickenpox or with respiratory or neurological symptoms, hepatitis, coagulopathy, extensive haemorrhagic rash or densely cropping vesicles should be referred for assessment by infectious diseases.
  • Chickenpox during the first 20 weeks of pregnancy should be discussed with a virologist or infectious diseases specialist in conjunction with the obstetric team.


  • Immunocompetent and pregnant: 7 days for uncomplicated and 14 days for complicated infection.
  • Immunocompromised: 14 days.

Patient group

Recommended (1st line) treatment


Immunocompetent adults: uncomplicated disease

Adults who present within 24-48 hours of onset of rash, treat with Aciclovir electronic Medicines Compendium information on AciclovirPO 800mg five times a day.
Valaciclovir can be considered in some patients1


Consider treating patients if they present within 24-48 hours of new vesicles appearing, especially if they are high risk group (e.g. smokers have a high risk of developing pneumonitis and should be monitored closely for this).

Immunocompetent adults : complicated disease (including evidence of pneumonitis, encephalitis or hepatitis)

Aciclovir electronic Medicines Compendium information on Aciclovir IV10mg/kg 8-hourly

With rapid improvement an early switch to oral therapy may be considered

Immunocompromised2 adults

Aciclovir electronic Medicines Compendium information on Aciclovir IV10mg/kg 8-hourly.

Consider oral valaciclovir (1 gram three times a day) for mild disease3 if careful monitoring can be facilitated.
With rapid improvement an early switch to oral therapy may be considered

Pregnant women4,5

  • Aciclovir electronic Medicines Compendium information on Aciclovirtreatment at <20 weeks gestation should be considered on a case by case basis.
  • Pregnant women >20 weeks gestation with uncomplicated chickenpox who present within 24-48 hours of onset of rash, treat with oral Aciclovir electronic Medicines Compendium information on Aciclovir800mg five times a day and warn regarding signs of severe infection.
  • Pregnant women with severe or complicated chickenpox should be treated with intravenous Aciclovir electronic Medicines Compendium information on Aciclovir10mg/kg 8hrly then PO when improving to complete a total of 14 days (IV and oral)
  • Pregnant women gestation >36/40 or risk of premature labour should be treated with IV Aciclovir electronic Medicines Compendium information on Aciclovir 10mg/kg 8-hourly

Aciclovir is not licensed for use in pregnancy in the UK, so the risks and benefits should be discussed with the patient beforehand.
With rapid improvement an early switch to oral therapy may be considered.

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Post exposure prophylaxis with antivirals or varicella zoster immunoglobulin (VZIG) may be given to attempt to avoid or attenuate severe chickenpox in high risk patients who have been exposed to an index case.
Post-exposure prophylaxis can be considered in patients who fulfil the following criteria:

  • They are at an increased risk of severe chickenpox (e.g. immunosuppressed patients, pregnant women, neonates) AND
  • Have had a significant exposure to chickenpox or shingles during the infectious period (24 hours prior to rash onset until no new lesions are occurring and all existing lesions are crusted over) AND
  • Have no antibodies (immunity) to varicella zoster virus - urgent VZV antibody testing can be performed

If a patient is thought to fulfil this criterion, the case should be discussed with the on call consultant virologist.

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A live attenuated Varicella vaccine is available. At present, it is chiefly used to vaccinate non-immune individuals who are in regular close contact with patients at high risk of severe chickenpox. This may include non-immune healthcare workers or close family and friends of immunocompromised patients. The Varicella vaccine is contraindicated in immunosuppressed and pregnant patients due to its live attenuated formulation.

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  1. Valaciclovir (PO 1g 8-hourly) can be considered as an alternative where compliance is considered an issue and in adult patients who smoke
  2. Immunocompromised adults: Patients with disorders of cell mediated immunity are at high risk of severe VZV and should receive intravenous therapy initially. This includes those with primary immunodeficiency, advanced HIV with CD4 <200, solid organ transplants, leukaemia, lymphoma, bone marrow transplants within the last 12 months, chemo- or radiotherapy within the last 6 months, steroid use >40mg prednisolone/day for > 1 week within the last 3 months, steroid use >20mg prednisolone/day for > 2 weeks within the last 3 months and those receiving immunomodulatory drugs
  3. Mild disease constitutes: <50 lesions, normal liver function tests and renal function
  4. Primary chickenpox in pregnancy is uncommon, however, risks of complications from VZV increase greatly during pregnancy and are highest during the 3rd trimester. Complications include pneumonitis, hepatitis and encephalitis, with smoking a significant risk factor for VZV pneumonitis during pregnancy. Overall, chickenpox is five times more likely to be fatal in pregnancy than in the non-pregnant adult.
  5. If the pregnant woman develops chickenpox or shows serological conversion in the first 20 weeks of pregnancy, she has a small risk of fetal varicella syndrome (FVS) and she should be informed of the implications. Women who develop chickenpox in pregnancy should be referred to a fetal medicine specialist, at 16–20 weeks gestation or 5 weeks after infection, for discussion and detailed ultrasound examination.


Record: 1465
Clinical condition: Varicella (chickenpox) infection
Target patient group: Adults
Target professional group(s): Secondary Care Doctors
Adapted from:

Evidence base


  • Tunbridge AJ, Breuer J, Jeffery KJ. Chickenpox in adults - clinical management. 2008, Journal of Infection: 57 (2):95-102.
  • UKMi (2016) Do NSAIDs increase the risk of severe skin reactions in children with chickenpox? UK Medicine Information.
  • Gould, D. Varicella zoster virus: chickenpox and shingles. 2014, Nursing Standard. 28 (33), 52-58.
  • AL-Nakib W, Al-Kandari S, El-Khalik DM, El-Shirbiny AM. A randomised controlled study of intravenous acyclovir (Zovirax) against placebo in adults with chickenpox. 1983, Journal of Infection; 6:49-56.
  • Wallace MR, Bowler WA, Murray NB, Brodine SK, Oldfield EC. Treatment of adult varicella with oral acyclovir: A randomized, placebo-controlled trial. 1992, Annals of Internal Medicine; 117:358-63.
  • Andreoni M, Canfarini M, Grint PC, Martorelli M, Di Luzio Paparatti U, Rocchi G. A double blind, placebo controlled trial of efficacy and safety of oral acyclovir (Zovirax) in the treatment of chickenpox in adults. 1992, European review for medical and pharmacological sciences: 14:63-9.
  • Klassen TP, Hartling L, Wiebe N, Belseck EM. Acyclovir for treating varicella in otherwise healthy children and adolescents. 2005, Cochrane Database of Systemic Reviews; (4):CD002980.
  • Albrecht MA. Treatment of Varicella (chickenpox) infection. March 30 2017, UpToDate Topic 8336 Version 19.0
  • Harger JH, Ernest JM, Thurnau GR et al. Risk factors and outcome of varicella-zoster virus pneumonia in pregnant women. 2002, Journal of Infectious Diseases; 185: 422-7.
  • Stone KM, Reiff-Eldridge R, White AD, et al. Pregnancy outcomes following systemic prenatal acyclovir exposure: Conclusion from the international acyclovir pregnancy registry, 1984-1999. 2004, Birth defects research. Part A, Clinical & molecular teratology; 70:201-7.
  • British National Formulary – 8 February 2018
  • Royal College of Obstetricians and Gynaecologists. Green-top Guideline No.13: Chickenpox in pregnancy. January 2015.
  • Gnann, J. Current antiviral treatments for Varicella. 2006, Herpes; 13(S1):13A-15A.
  • Public Health England: Guidance for issuing Varicella-zoster immunoglobulin (VZIG) – August 2017
  • UKHSA Guidelines on post exposure prophylaxis (PEP) for varicella/shingles (April 2022)
  • The Green Book: chapter 34 (Varicella) – August 2015
  • National infection prevention and control manual for England 14 April 2022

Approved By

Improving Antimicrobial Prescribing Group

Document history

LHP version 2.1

Related information

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