People use insect repellents to keep harmful or annoying bugs away. Natural insect repellents do not contain toxic chemicals, and some research indicates they are effective.

Insect repellents help keep irritating or disease-carrying insects away. They are an important resource, as the viruses and parasites that certain insects can carry are a global public health concern.

According to the Environmental Protection Agency (EPA), the definition of a pesticide includes:

  • substances, or a combination of substances, that prevent, destroy, repel, or mitigate pests
  • substances or a combination of substances that can act as plant regulators
  • nitrogen stabilizers

All pesticides that are legally available in the United States have EPA approval. However, pesticides can still contain harmful chemicals. The EPA has issued a list of minimum-risk pesticide ingredients. Most of these are naturally occurring, and many are usable in food products.

This article explores 10 natural insect repellents included in the EPA list of minimum-risk pesticide ingredients in more detail. It also discusses the potential risks of using them, the benefits and risks of N, N-diethyl-meta-toluamide (DEET), and when to contact a doctor.

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Castor oil is a vegetable oil that comes from castor bean seeds. It has lubricating and medicinal uses, but people may also use it as a pesticide.

Research suggests that the oil is effective for repelling a few different types of insects. For example, an older 2014 study assessing the effect on the bruchid beetle, which is a stored grain pest, found that castor oil caused mortality in the beetles and reduced the number of beetle eggs that hatched.

Other insects that castor oil can repel include the dengue fever-carrying mosquito Aedes aegypti.

Cinnamon is a common food spice, but people also use it in processing, medicine, and agriculture. People may use it in various forms, including as an oil.

A 2021 study suggests that cinnamon, particularly in oil form, works as an insect repellant, and in higher doses, it can also destroy some insects and prevent them from laying eggs.

Citronella and citronella oil typically come from the Cymbopogon nardus plant. Research suggests that in prime conditions, citronella is effective as an insect repellent, with low toxicity to humans, but air quality and high temperatures can affect how well it works.

According to 2018 research, citronella is likely to work for about 30 minutes to 2 hours, but the level of protection is not high against all types of mosquitos.

Cloves and clove oil are present in various food products, cosmetics, and medicine. People may also use them as an insect repellent. As well as flying insects, clove oil cockroaches.

A 2021 meta-analysis suggested that cloves may be a moderate repellant against mosquitos in the Anopheles genus.

Some research suggests that clove oil may repel mosquitos for up to 2–3 hours after application. However, researchers indicate that further studies into the efficacy of clove oil are necessary.

Most people know garlic as a flavorful ingredient, but garlic essential oil can also act as a repellent against insects, including beetles and mosquitos.

The scent of garlic may reduce mosquito attraction to human odor. Findings show that garlic oil is a strong mosquito repellent for the initial 30 minutes after application, but that the effect weakens after this time. Some people take garlic tablets to keep mosquitos away, but little evidence supports their effectiveness.

Peppermint comes from crossbreeding spearmint with water mint. Research suggests that it is an effective insect repellent, with one 2022 study finding that peppermint oil may provide complete protection from Anopheles dirus mosquito species for 180 minutes.

Another 2020 study suggested that peppermint oil acts as a strong Aedes aegypti mosquito repellent for 30 minutes, after which it continues to repel them, but not as significantly.

Rosemary is an evergreen shrub that many people use as an ingredient in food. Research suggests that essential oils from rosemary may effectively repel mosquitos.

Sesame oil comes from sesame seeds, which people may use as a cooking oil. It is often a natural ingredient within commercial insect repellents.

However, findings from 2020 suggest that sesame oil does not provide significant protection against Aedes aegypti mosquito bites or repel these insects.

Older 2013 research suggests that the oil may repel cockroaches at certain concentrations, but it was not as effective as clove oil.

Spearmint, including spearmint oil, contains similar chemicals to peppermint. Research suggests that spearmint oil can act as an effective Aedes aegypti mosquito repellent for the first 30 minutes after application, after which the effect starts to fade.

Thyme is a Mediterranean plant. 2019 research suggests that it may repel some Anopheles mosquito species.

Research from 2020 suggested that other studies have also found thyme oil to work well against insects. However, the researchers did not consider thyme oil to be an effective Aedes aegypti mosquito repellent when they applied it to a cotton ball.

Issues may arise if people have skin sensitivity or allergies to any of the natural insect repellents above.

If a person uses essential oils, such as cinnamon oil, they should dilute them with a carrier oil — for example, sweet almond oil. Before applying to the skin, a person should conduct a patch test to help prevent severe allergic reactions. Similarly, people should not ingest essential oils.

Additionally, 2018 research suggests that methyl eugenol, which is present in citronella and a trace component of clove oil, could be carcinogenic to humans. However, further studies are necessary to confirm this.

A person should speak with a doctor if they are unsure whether natural insect repellents are suitable for them or how to use them safely.

DEET is a common ingredient in insect and parasite repellents. It reduces how well bugs, such as mosquitoes and ticks, can smell people.

Research suggests that DEET provides around 5 hours of protection against insects and, in turn, offers protection against the diseases that mosquitos can carry. It is slightly toxic to humans, and there is a risk of neurotoxicity if people apply DEET underneath sunscreen. Neurotoxicity refers to damage or disruption to the nerves.

For this reason, DEET may be more suitable for some people than others, and people should avoid spraying it directly onto the face. However, the EPA suggests that DEET is not toxic if people use it correctly.

If a person experiences a severe allergic reaction to either insect bites or insect repellents, they should contact a healthcare professional immediately.

People should also speak with a doctor if they wish to know more about insect repellents and which types may be most suitable on an individual basis.

Insect repellents may help prevent insect bites and the transmission of insect-borne diseases. Many insect-repelling products are available, and some chemicals are naturally occurring. Natural insect repellents may work well for some people.

A person should seek medical attention as soon as possible if they experience a severe allergic reaction to an insect bite or a form of repellent.