Guidance

Bite prevention

Updated 17 June 2026

Note: Effective bite prevention should be the first line of defence against malarial infection. The traveller should embark on their journey already equipped with mosquito protection measures appropriate to their particular circumstances and carry their insect repellent in their hand luggage.

For some destinations, the UK Malaria Expert Advisory Group (UKMEAG) advises awareness of risk and bite prevention for malaria prevention and does not recommend chemoprophylaxis. Practitioners are strongly advised that for those destinations, and also for locations where chemoprophylaxis is also recommended, the benefits from using bite prevention measures, not only against malaria, but also in protecting against infection with other vector-borne diseases are emphasised to travellers.

When female Anopheles mosquitoes bite

Biting time varies between species, so travellers should assume they are at risk of being bitten mainly, but not only, from dusk to dawn inclusive. The biting of several major malaria vectors in Africa peaks at and just after midnight so protection in bed is especially important. However, in many parts of South America and South-East Asia, the greatest risk from being bitten by malaria vectors is in the evening, before the population retires indoors. Furthermore, as other species of mosquito (for example, those which transmit yellow fever, dengue fever and other arboviral infections) bite during the daytime, it is important to maintain bite precautions during daylight hours, both indoors and outdoors. See also Patterns of activity in Awareness of risk.

Measures to prevent mosquito bites

Repellents

As malaria prevention in travellers becomes reliant on bite avoidance and awareness of risk in more and more destinations, much greater attention to the correct use of insect repellents is required.

Debboun and Goodyer (12) have highlighted the fact that users decide whether or not to use an arthropod repellent for personal protection, what kind to use, and how much to apply. Therefore, the travel health advisor should emphasise the importance of adhering to the UKMEAG recommendations for their use, to achieve optimal protection, especially as repellents have an excellent safety profile.

In some circumstances, UKMEAG advice may differ from that in repellent manufacturers’ product information. When this occurs, the recommendations in these guidelines (which are based on current expert advice from the UKMEAG) should be followed.

UKMEAG recommends a 50% N,N-diethyl-m-toluamide (DEET)-based insect repellent as a first choice. If DEET is not tolerated (or is not available), an alternative preparation (see below) should be used.

Consult the instructions for use for individual products. Reapplication should be made, when necessary, to ensure that mosquitoes are not biting, bearing in mind safe limits for the product concerned.

The 4 active ingredients described below are incorporated into repellent formulations available on the UK market (normally one active ingredient per product). If a product does not contain one of these active ingredients, it should not be used. They have excellent mosquito repellent properties, though DEET is supported by the strongest evidence base and its extensive use worldwide over the last 50 years.

In the field many factors will affect the perceived longevity of a repellent before reapplication is required, including the mosquito biting pressure (that is, the number of mosquitoes present), sweat and run off of the repellent, swimming, species of mosquito and ‘attractants’ produced by the individual (13). One of the most important factors, and one that can be controlled by the user, is the amount of repellent applied to exposed skin. However, it has been demonstrated (14) that travellers will tend to apply almost half of the amount at which a product has been tested according to current protocols. Therefore, the stated longevity on manufacturers’ packaging may not be achieved in the field and more frequent application will be required.

The general recommendations of the UKMEAG concerning repellent use are:

• use a 50% DEET-based repellent and if not tolerated or preferred by the traveller, the highest strength available of either icaridin or eucalyptus citriodora oil, hydrated, cyclized or 3-ethlyaminopropionate - long-acting formulations may increase longevity of the active ingredient, but further evidence is required to demonstrate their advantages
• as a guide, users should reapply repellents when the mosquitoes begin to land, to ensure that they do not bite
• some volatile oils from plant products, including citronella, do have repellent properties but they are usually short lasting - there is insufficient data to support the use of blends of such oils as reliable repellents

DEET

DEET (N,N-diethyl-m-toluamide) has been in use as an insect repellent for more than 50 years and is reportedly used worldwide by approximately 200 million people each year (15). It is available in a variety of concentrations and in various preparations including sprays and a slow release preparation. A variety of studies has concluded that there is a low risk of adverse effects when DEET is applied according to product directions (15).

UKMEAG recommends using a 50% DEET-based insect repellent if available. There is no further increase in duration of protection beyond a concentration of 50% DEET (15).

Sweat-off time varies with activity (for example, sedentary activity versus vigorous exercise). The interval between applications depends on this as well as the DEET formulation and concentration used.

DEET and sunscreen

Several studies have evaluated the impact of co-application of sunscreen and DEET. DEET (33%) has been shown to decrease the protection from SPF 15 sunscreen but there is no evidence that sunscreen reduces the efficacy of DEET when used at concentrations above 33% (16, 17). Frequent (every 2 hours) reapplication of sunscreen over DEET applied at 17% was found to reduce the mean repellency rate and also mean protection time (by about one hour) compared with DEET alone (17).

Stanczyk and colleagues (18) recommended advising travellers to apply repellent first and be aware that repellent may wear off more quickly if reapplying only sunscreen on top or use a combined repellent and sunscreen product

Note: In contrast to Stanczyk and colleagues (18), UKMEAG’s view is that as repellent activity will reduce more quickly than that of a sunscreen if reapplying only sunscreen on top, repellent will therefore usually need to be reapplied on top of a sunscreen. When both sunscreen and DEET are required, DEET should be applied after the sunscreen. Thirty to 50 SPF sunscreen should be applied to compensate for DEET-induced reduction in SPF. Sunscreen is not required from dusk to dawn.

DEET and infants

DEET is not recommended for infants below the age of 2 months. If a particular DEET manufacturer’s product information recommends a higher age cut off for use in children, the UKMEAG guidance should be followed.

DEET and pregnancy

Use of 20% DEET in the second and third trimesters of pregnancy was not associated with adverse effects on infants from those pregnancies followed for up to 12 months after birth (19). Given the seriousness of malaria in pregnancy, UKMEAG recommends the use of DEET at a concentration of up to 50% as part of the malaria prevention regimen for pregnant women, including those in the first trimester. DEET may be used at a concentration of up to 50% by women who are breastfeeding and for infants and children aged over 2 months.

UKMEAG advice on use of DEET for protection from mosquito bites is that:

• DEET is suitable for all individuals over the age of 2 months (unless allergic), and furthermore, the United States Environmental Protection Agency (EPA) states that DEET is approved for use on children with no age restriction (accessed 28th September 2025)
• there is no current evidence that any group (including pregnant women and small children) is at increased risk from using 50% DEET; the EPA examined data on seizures potentially related to DEET exposure and concluded that observed incidence of recognized seizures is about one per 100 million users (20)
• DEET applications can damage some plastic watch straps, watch covers and plastic jewellery; these items should not be allowed to come into contact with DEET
• the user should ensure that repellents are not ingested or inhaled and do not come into contact with their eyes or mouth
• repellents should be used only on exposed areas of skin, though some products can be sprayed onto clothing. However, DEET may melt synthetic fibres

Eucalyptus citriodora oil, hydrated, cyclized (PMD)

Eucalyptus citriodora oil, hydrated, cyclized was previously known as p-menthane 3,8 diol or PMD – see the European Chemicals Agency June 2016 minutes (accessed 28th September 2025). Eucalyptus citriodora oil, hydrated, cyclized is a repellent that occurs naturally in the lemon eucalyptus plant and has structural similarities with the chemical menthol. This product can now be produced synthetically.

Plant-based repellents have become more popular in recent years (12). For those travellers preferring plant-based repellents, Eucalyptus citriodora oil, hydrated, cyclized is the only active ingredient recommended by UKMEAG.

Eucalyptus citriodora oil, hydrated, cyclized is an effective repellent (21, 22, 23). 15% DEET slightly outperformed 15% Eucalyptus citriodora oil, hydrated, cyclized as a repellent against Anopheles stephensi under laboratory conditions (24) but Eucalyptus citriodora oil, hydrated, cyclized remains a very useful repellent. Eucalyptus citriodora oil, hydrated, requires more frequent application than DEET.

Eucalyptus citriodora oil, hydrated, cyclized is well tolerated with low toxicity when used according to the manufacturers’ instructions. Accidental application to the eye can result in corneal damage, so the EPA concluded that product labels should clearly emphasise the hazard and first aid treatment for accidental eye exposure (25).

Icaridin (Picaridin)

Icaridin (KBR3023) (1piperidinecarboxylic acid, 2-(2hydroxyethyl)-,1-methyl-propylester) has repellent properties comparable to those of DEET (26, 27) with a comparable duration of protection (28, 29, 30) when both are used at 20%. Icaridin is available in various concentrations between 2% and 20% (31, 32). If a traveller elects to use icaridin for mosquito bite prevention, UKMEAG advises use of a 20% preparation.

Icaridin is well tolerated. Adverse events are uncommon and mild, with mostly cutaneous side effects (33) There have been some studies reporting fewer skin side effects when using icaridin versus DEET, albeit using lower concentrations of icaridin (34).

3-ethlyaminopropionate (IR3535)

In some studies 3-ethlyaminopropionate (IR3535) has shown a shorter duration of protection against mosquitoes than DEET when used at the same concentration (29, 35, 36) but is still a safe and effective repellent which has been in use for more than 25 years.

IR3535 requires more frequent application than DEET.

Accidental application of IR3535 to the eye can result in moderate eye irritation (30) so appropriate warnings about avoiding accidental eye exposure and the need for first aid measures are required.

Oil of citronella

While oil of citronella-based products do have repellent properties, they provide short- lived protection) and are not recommended by UKMEAG. Citronella has been withdrawn in Europe.

Insecticides

Permethrin and other synthetic pyrethroids have a rapid knock-down effect on mosquitoes and are used to kill resting mosquitoes in a room. Permethrin can also be used to treat clothing.

Insecticide-treated nets

Using multiple methods to prevent arthropod bites concurrently is more effective than using a single method, which underlies the use of insecticide-treated bed nets. These have become an important and cost-effective method of bite prevention globally (37).

All travellers to malaria-endemic areas should sleep under a mosquito net unless they are in a well screened room with mosquito netting on windows and doors into which mosquitoes cannot enter, or a room with switched on functioning air conditioning into which mosquitoes cannot enter. If the room door has been opened, the room should then be checked for mosquitoes.

Insecticide-treated mosquito nets should be used and kept in good condition. Protective efficacy against malaria for travellers has been estimated at 50% (38). Insecticide-treated mosquito nets also act as baited trap reducing mosquito population in room.

Mosquito bed nets should be free of tears, tucked in under the mattress and taut, not drooping. Insecticide (pyrethroid)-impregnated bed nets improve protection because they help to prevent biting through the net on parts of the body touching the net, and mosquitoes surviving long enough near a net to find any tears in the net which may exist (38).

Most of the nets now available are long-lasting impregnated nets (LLINs). In these products the pyrethroid is incorporated into the material of the net itself or bound to it with a resin (39). They have an expected useful life of at least 3 years. Impregnated nets other than LLINs will need to be re-impregnated every 6 to 12 months (depending on how frequently the net is washed) to remain effective (40). Follow the instructions for the product concerned.

Clothing

Within the limits of practicality, cover up with loosely fitting clothing with long sleeves, long trousers and socks if out of doors, to minimise accessibility to skin for biting mosquitoes. A field study conducted in Mali examined the effect of clothing colour on mosquito attraction. The results indicated that under bright-night conditions, Anopheles gambiae mosquitoes were significantly more attracted to black targets compared to white and striped targets. This study suggested that light-coloured clothing may reduce mosquito attraction in tropical regions. UKMEAG recommends wearing light-coloured clothing.

Clothing may be sprayed or impregnated with an insecticide, for example, permethrin (40), or purchased pre-treated to reduce biting through the clothing. This can provide a high level of bite prevention (42) and is recommended by UKMEAG.

In a placebo-controlled trial conducted in Uganda, use of permethrin-treated body wraps for children being carried significantly decreased their incidence of clinical malaria (41).

As an alternative to insecticides, WHO states that any of the repellents considered safe for skin application may be used to treat clothing (37). DEET is useful as a clothing repellent and is available as preparations for use only on clothing, but its duration on clothing is shortened due to its volatility (43). Cotton clothing (for example socks) can be sprayed with DEET, but users should be aware that it may melt synthetic fibres.

A repellent should still be applied to exposed skin even if the clothing has been treated.

A useful practical guide is available at the Bug Off website.

Room protection

Room protection represents an important component of malaria prevention, but should never be relied upon on its own.

Air conditioning can reduce the likelihood of mosquito bites if it achieves substantial reduction in night time temperature and significantly increases air flow. Ceiling fans can reduce mosquito nuisance.

Doors, windows and other possible mosquito entry routes to sleeping accommodation should be screened with fine mesh netting which must be close-fitting and free from tears.

The room should be sprayed before dusk with a knockdown insecticide (usually a pyrethroid) to kill any mosquitoes which may have entered the accommodation during the day.

In addition, during the night, where electricity is available, use a plug-in proprietary heated liquid reservoir device containing insecticide or a plug-in electrically heated device to vapourise a ‘mat’ (tablet) containing a synthetic pyrethroid in the room.

Burning of a mosquito coil containing insecticide must not be undertaken indoors, but can be deployed outside to repel and kill mosquitoes (44).

Myths

Herbal remedies

The UKMEAG strongly advises against relying on any herbal remedies for the prevention of malaria. Herbal remedies have not been tested for their ability to prevent or treat malaria.

Homoeopathy

The UKMEAG strongly advises against relying on any homoeopathic remedies for the prevention of malaria. There is no scientific proof that homoeopathic remedies are effective in either preventing or treating malaria. In addition, the Faculty of Homoeopathy does not promote the use of homoeopathic remedies for malaria prevention.

Buzzers

Electronic buzzers (emitting high frequency sound waves) are completely ineffective as mosquito repellents. Companies selling them have been prosecuted and fined under the UK Trades Descriptions Act and UKMEAG advice is that they should not be used. The use of apps available on mobile phones to prevent mosquitoes biting is also strongly discouraged by UKMEAG.

Music

Heavy metal music is also ineffective as a mosquito repellent.

Vitamin B1

There is no evidence that vitamin B1 taken orally repels mosquitoes (43, 44).

Vitamin B12

There is no evidence that vitamin B12 taken orally repels mosquitoes.

Other vitamins and brewers yeast tablets

These are ineffective as mosquito repellents.

Garlic

There is no evidence that garlic taken orally repels mosquitoes (45).

Savoury yeast extract spread

It is sometimes stated that Marmite® taken orally repels mosquitoes either by giving off a cutaneous odour repellent to mosquitoes or via its vitamin B1 content. There is no evidence that either assertion is true.

Tea tree oil

There is no evidence that tea tree oil is an effective mosquito repellent.

Bath oils and emollients

There is no evidence that proprietary bath oils provide effective protection against mosquito bites.

Alcohol

Alcoholic drinks do not protect against mosquito bites. Indeed, beer consumption is reported to increase human attractiveness to malaria mosquitoes (46).

Gin and tonic has no mosquito-repellent properties and the amount of quinine in tonic water has no effect on malaria parasites.

References

Numbers refer to the complete list of references found in the References section.

12. Goodyer LI, Debboun M. ‘Anthropod repellents in public health.’ In Advances in Arthropod Repellents 2022: Academic Press, pages 1 to 18

13. Thrower Y, Goodyer LI. ‘Application of insect repellents by travellers to malaria-endemic areas’ Journal of Travel Medicine 2006: volume 13, pages 198 to 203

14. Hasler T, Fehr J, Held U, Schlagenhauf P. ‘Use of repellents by travellers: a randomised, quantitative analysis of applied dosage and an evaluation of knowledge, attitudes and practices (KAP)’ Travel Medicine and Infectious Disease 2019

15. Chen-Hussey V, Behrens R, Logan JG. ‘Assessment of methods used to determine the safety of the topical insect repellent N, N-diethyl-m-toluamide (DEET)’ Parasites and Vectors 2014: volume 7, issue 1, page 173

16. Murphy ME, Montemarano AD, Debboun M, Gupta R. ‘The effect of sunscreen on the efficacy of insect repellent: a clinical trial’ Journal of the American Academy of Dermatology 2000: volume 43, issue 2, pages 219 to 222

17. Webb CE, Russell RC. ‘Insect repellents and sunscreen: implications for personal protection strategies against mosquito‐borne disease’ Australian and New Zealand Journal of Public Health 2009: volume 33, issue 5, pages 485 to 490

18. Stanczyk NM, Behrens RH, Chen-Hussey V, Stewart SA, Logan JG. ‘Mosquito repellents for travellers’ British Medical Journal 2015: volume 350, h99

19. McGready R, Hamilton KA, Simpson JA, Cho T, Luxemburger C, Edwards R and others. ‘Safety of the insect repellent N, N-diethyl-M-toluamide (DEET) in pregnancy’ The American Journal of Tropical Medicine and Hygiene 2001: volume 65, issue 4, pages 285 to 289

20. United States Environmental Protection Agency. ‘Reregistration Eligibility Decision (RED) DEET’ Prevention, Pesticides and Toxic Substances 1998

21. Govere J, Durrheim D, Baker L, Hunt R, Coetzee M. ‘Efficacy of 3 insect repellents against the malaria vector Anopheles arabiensis’ Medical and Veterinary Entomology 2000: volume 14, issue 4, pages 441 to 444

22. Moore SJ, Darling ST, Sihuincha M and others. ‘A low-cost repellent for malaria vectors in the Americas: results of 2 field trials in Guatemala and Peru’ Malaria Journal 2007: volume 6, page 101

23. Johirul Islam, Kamaruz Zaman, Sanjukta Duarah, Pakalapati Srinivas Raju, Pronobesh Chattopadhyay. ‘Mosquito repellents: an insight into the chronological perspectives and novel discoveries’ Acta Tropica 2017: volume 167, pages 216 to 223

24. Colucci B, Müller P. ‘Evaluation of standard field and laboratory methods to compare protection times of the topical repellents PMD and DEET’ Scientific Reports 2018: volume 8, issue 1, pages 1 to 11

25. BPPD. ‘p-Menthane-3,8-diol (011550) Biopesticide Registration Eligibility Document’

26. Klun J. A, Khirimian A, Debboun M. ‘Repellent and deterrent effects of SS220, Picaridin, and DEET suppress human blood feeding by Aedes aegypti, Anopheles stephensi and Phlebotomus papatasi’ Journal of Medical Entomology 2006: volume 43, issue 1, pages 34 to 39

27. Goodyer L, Schofield S. ‘Mosquito repellents for the traveller: does picaridin provide longer protection than DEET?’ Journal of Travel Medicine 2018: volume 1, issue 25, pages S10 to S15

28. Badolo A, Ilboudo‐Sanogo E, Ouédraogo AP, Costantini C. ‘Evaluation of the sensitivity of Aedes aegypti and Anopheles gambiae complex mosquitoes to 2 insect repellents: DEET and KBR 3023’ Tropical Medicine and International Health 2004: volume 9, issue 3, pages 330 to 334

29. Costantini C, Badolo A, Ilboudo-Sanogo E. ‘Field evaluation of the efficacy and persistence of insect repellents DEET, IR3535, and KBR 3023 against Anopheles gambiae complex and other Afrotropical vector mosquitoes’ Transactions of the Royal Society of Tropical Medicine and Hygiene 2004: volume 98, issue 11, pages 644 to 652

30. WHO. ‘Report of the fourth WHOPES working group meeting. Review of: IR3535, KBR3023,(RS)-methoprene 20% EC, pyriproxyfen 0.5% GR and lambda-cyhalothrin 2.5% CS’ WHO Pesticide Evaluation Scheme (WHOPES) Working Group meeting. 4 to 5 December 2001

31. Anon. ‘Picaridin: a new insect repellent’ The Medical Letter on Drugs and Therapeutics 2005: volume 47, issue 1,210, pages 46 to 47

32. Frances SP. Picaridin. In: Debboun M, Strickman D, Frances SP, editors. ‘Insect Repellents: Principles, Methods, and Uses’ Boca Raton: CRC Press 2007, pages 337 to 440

33. Heng S, Sluydts V, Durnez L and others. ‘Safety of a topical insect repellent (picaridin) during community mass use for malaria control in rural Cambodia’ PLoS One 2017: volume 12, issue 3, pages 1 to 16

34. Frances S. P, Cooper R. D. ‘Personal protection measures against mosquitoes: a brief history and current use of repellents by the Australian defence force’ ADF Health 2002: volume 3, pages 58 to 63

35. Fradin MS, Day JF. ‘Comparative efficacy of insect repellents against mosquito bites’ New England Journal of Medicine 2002: volume 347, issue 1, pages 13 to 18

36. Strickman D. ‘Topical repellent active ingredients in common use’ In: Debboun M, Frances SP, Strickman D, editors. ‘Insect Repellent Handbook (second edition)’ CRC Press Taylor and Francis Group: 2014

37. WHO. ‘Vector control: methods for use by individuals and communities’ Prepared by Jan Rozendaal 1997

38. Petersen E. ‘Malaria chemoprophylaxis: when should we use it and what are the options?’ Expert Review Anti-Infective Therapy 2004: volume 2, pages 119 to 132

39. WHO. ‘Report of the thirteenth WHOPES working group meeting. 28 to 30 July’ 2009

40. Schreck C, Carlson D, Weidhaas D, Posey K, Smith D. ‘Wear and aging tests with permethrin-treated cotton-polyester fabric’ Journal of Economic Entomology 1980: volume 73, issue 3, pages 451 to 453

41. Ross M. Boyce, Bonnie E. Shook-Sa, Ronnie Ndizeye, Emmanuel Baguma, Dana Giandomenico, Caitlin A. Cassidy, Solomon Eshun, and others. ‘Permethrin-Treated Baby Wraps for the Prevention of Malaria’ New England Journal of Medicine 2025

42. Marta F Maia, Merav Kliner, Marty Richardson, Christian Lengeler, Sarah J Moore, Cochrane Infectious Diseases Group. ‘Mosquito repellents for malaria prevention’ Cochrane Database of Systematic Reviews 2018 February: 2018 issue 2, CD011595

43. McCain WC, Leach GJ. ‘Repellents used in fabric: the experience of the US military’ In: M D, SP F, D S, editors. ‘Insect Repellents: Principles, Methods, and Uses’ Boca Raton: CRC Press 2007, pages 261 to 273

44. Hewitt S, Farhan M, Urhaman H, Muhammad N, Kamal M, Rowland M. ‘Self-protection from malaria vectors in Pakistan: an evaluation of popular existing methods and appropriate new techniques in Afghan refugee communities’ Annals of Tropical Medicine and Parasitology 1996: volume 90, issues 3, pages 337 to 344

45. Ives AR, Paskewitz SM. ‘Testing vitamin B as a home remedy against mosquitoes’ Journal of the American Mosquito Control Association 2005: volume 21, issue 2, pages 213 to 217

46. Lefèvre T, Gouagna LC, Dabiré KR, Elguero E, Fontenille D, Renaud F, Costantini C, Thomas F. ‘Beer consumption increases human attractiveness to malaria mosquitoes’ PLoS One 2010 March 4: volume 5, issue 3, article e9546