IR3535 Ethyl-butylacetylaminopropionate (EBAAP)

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Ethyl butylacetylaminopropionate (EBAAP) is an insect repellent sold under the trade name IR3535 (Trademark owned by Merck). It is very effective against ticks, mosquitoes, biting midges, horseflies, fleas, and many other bugs.  Even wasps and bees don’t like the smell and stay away.

What is ethyl butylacetylaminopropionate?

Ethyl butylacetylaminopropionate is a synthetic amino acid, it is a derivative of carboxylic acid and acetamide, structurally it builds on the naturally occurring amino acid beta-alanine. It appears as colorless and odorless liquid and is easily soluble in water and as such can be used in mixed with carriers in lotions, sprays, and creams.

How IR3535 repels insects and ticks

Bug and tick repellents work by interfering with the sensory organs of insects. After application to skin or clothing, repellents evaporate slowly. This creates a kind of scent bell around the wearer, which triggers unpleasant stimuli in insects and prevents the possible host from being located by masking its body odor. Unlike insecticides, repellents do not kill ectoparasites, so the risk of insects and arachnids developing resistance is comparatively low.

EBAAP / IR3535 has been used as an insect repellent for many years. It is effective against long-term protection against mosquitoes, ticks, wasps, black flies and sandflies, fleas, and many other blood-sucking insects.

Mode of application of IR3535

It is available in the form of lotions, aerosols, pump sprays, gel, and powders. Its formulations usually range from 10-30%. The formulations are directly applied to human skin or clothing. Its application usually lasts four to eight hours depending on the insect. Protection from blood-sucking insects lasts four to eight hours, but the duration can vary depending on what kind of insect buzzes around you.

Use repellents containing Ethyl butylacetylaminopropionate strictly as recommended. Not to be applied near eyes, mouth, wounds, or irritated skin.

IR3535 can also be used as a repellent for dogs, cats, and horses.

How safe is IR3535?

EBAAP provides long-lasting protection against stinging insects and is generally very well tolerated by the skin. When used as recommended, no side effects have been reported so far.

It is well tolerated and also suitable for toddlers over the age of one.

  • If overdosed or if there is hypersensitivity then IR3535 can cause mild skin irritation.
  •  Must not be inhaled, can cause respiratory irritation.
  • Contact with the eyes must be avoided. Causes serious eye irritation
  • May dissolve or damage some plastics and fabrics

Advantages of IR3535

  • Well tolerated
  • Also repels wasps and bees
  • Very effective against ticks
  • A repellent without killing action, there is no risk of insect resistance development
  • It is non-toxic to aquatic organisms such as fish or algae
  • Does not accumulate in the environment and is biodegradable


These two repellents offer protection against most mosquito species and many tick species. However, DEET is considered more effective against mosquitoes that can cause malaria and dengue fever it also provides much longer protection and does not need to be re-applied as often. DEET is the better choice if you are in areas where malaria, dengue, and sleeping sickness are a great risk.

However, IR3535 is more effective to ward off certain tick species of the type Ixodes, like the common deer tick.

Compared to IR3535, DEET has the disadvantage of strong odor, and staining of certain fabrics and is more likely to cause skin irritation in sensitive people. IR3535 is colorless and odorless and has no known side effects.

IR3535 VS Picaridin

Picaridin is also a very effective repellent that keeps most mosquitos and ticks at bay. It is usually well-tolerated and only in rare cases may irritate the skin. Picaridin evaporates from the skin very slowly and may repel bugs for longer periods than IR3535.

While both provide effective protection against mosquitos and ticks, IR3535 is more effective against certain tick species.


Even if IR3535 or EBAAP (for ethyl butylacetylaminopropionate) is less strong and has a shorter duration of action than DEET or Icaridin, it effectively protects against most stinging, biting, and blood-sucking parasites.

The advantage of IR3535 is being its good skin tolerance and the near-nill cases of unwanted side effects.

As a true insect repellent, it does not kill insects but only keeps them at a distance, it is also non-toxic to aquatic organisms such as fish and algae, and does not affect the ecosystem or accumulate in the environment since it is easily degradable.

It offers good protection against mosquitoes, sandflies, fleas, and other ectoparasites, as well as very good protection against ticks of the Ixodes family.

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