Phototoxicity: What is it and why should I care?

Did you know that some essential oils are ‘phototoxic’?  In this article we will cover the best practices as to how to use essential oils safely in order to avoid extreme sunburn this sunny season.

‘Photo...’ what? 

Dovetail two factors that equal a much higher risk of burning: Warmer weather + spending more time outside.  Please take the time to check to see which essential oils are in your skincare products.  The term 'phototoxicity' refers to the property of some essential oils, especially those in the Rutaceae plant family (think citrus), which may cause a chemically induced skin irritation that is activated by light (natural and artificial light, for example a tanning booth).

This means that if you apply a phototoxic citrus essential oil to your skin, and then you spend time in the sun, you could experience a painful skin reaction like burning, blistering, or discoloration (which can be permanent). This happens because the UV light is reacting with the oil that causes the reaction. This is also why you can experience phototoxic effects in a tanning bed. I’m sure you can understand why I get more than a little concerned when I see social media posts for lip balms that include lime essential oil.  Immediately, my brain goes:  ‘what?!!’

Here’s a list of five common citrus essential oils that are phototoxic to varying degrees: bergamot, grapefruit, lemon, lime, and bitter orange (there are non-citrus essential oils also known to be phototoxic. As with any use of essential oils, please do your research prior to blending!).


Most commonly, essential oils from the Rutaceae plant family (e.g. lemon, lime, orange) are cold-pressed.  While steam distillation is still the most common method of extraction of essential oils, it is a relatively new process of extracting essential oils from citrus peels. But if you can find steam distilled lemon or lime essential oil - the steam distillation process does neutralize the components of the essential oil that would cause either lemon or lime essential oil from being phototoxic. Bergamot is sometimes rectified and will be labelled bergaptene-free or FCF (which means furanocoumarin free) will appear on the label. This means the bergamot essential oil has been rectified and the chemical constituent, furanocoumarin has been removed  (the chemical constituent responsible for phototoxicity).

Maximum Dermal Use

Here’s what we know about the maximum dermal use levels of the above five citrus essential oils – in order to avoid phototoxic reactivity. These concentration levels are based on Tisserand & Young’s research (2014). 

While you can check your skincare product ingredient lists for these essential oils, it will be difficult to know exactly what percentage of the phototoxic essential oil is in the product: 

  • Bergamot: blend at 0.5% or less (Tisserand & Young, 2014, p. 211
  • Grapefruit: blend at 4% or less (Tisserand & Young, 2014, p. 297)
  • Lemon: blend at 2% or less (Tisserand & Young, 2014, p. 331)
  • Lime: blend at 0.7% or less (Tisserand & Young, 2014, p. 337)
  • Bitter Orange: blend at 1.25% or less (Tisserand & Young, 2014, p. 371)

Technically, any phototoxic oil can be applied to the skin, as long as they're applied to areas of the skin that will not be exposed to the sun!  Tisserand and Young recommend avoiding the sun and tanning beds for 12 hours after application of a phototoxic essential oil over the recommended safe concentration level (e.g. the range is 0.7% - 4% depending on the essential oil as seen in the above table).  Personally, I choose to stay absolutely safe; I avoid using these essential oils in my skincare products during the summer and am cautious during the colder months. 

But if you do choose to use phototoxic essential oils in your DIY products, or you are a formulator and selling your handmade products you need to know how to calculate concentration levels.  For example, the suggested concentration level limit of lime is 0.7%, therefore, you, as the formulator must be very accurate when measuring.

Safe Use of Phototoxic Citrus Essential Oils Per 30 ml of Carrier Oil:

  • Cold Pressed Bergamot: 3 drops per 30 ml
  • Cold Pressed Grapefruit: 24 drops per 30 ml
  • Cold Pressed Lemon: 12 drops per 30 ml
  • Cold Pressed Lime: 4.2 drops (round down to 4 drops per 30 ml)
  • Cold Pressed Bitter Orange: 7.5 drops (round down to 7 drops per 30 ml)


If you were to mix and match your phototoxic essential oils, the mathematical equation becomes increasingly more complicated. The above numbers are a total number of drops for 30 ml; which means you cannot mix 3 drops of bergamot and 12 drops of lemon in the same 30 ml and consider that a phototoxic safe blend as the combined concentration of furanocoumarin must remain within the recommended limit for safe use.

Safer Options 

  • Bergamot FCF/bergaptene-free
  • Distilled Lime or Lemon
  • Tangerine (not phototoxic according to Tisserand & Young, 2014, p. 437)
  • Sweet Orange (not phototoxic according to Tisserand & Young, 2014, p. 372)

While these essential oils are not phototoxic, all citrus oils that have been cold-expressed are susceptible to oxidation, which is a process of degradation of the essential oil, and will also cause skin sensitization. And as is the blending protocol with all essential oils, there is always a maximum safe dermal level – depending not only on the blend’s intended use, but also who will be the end user.  Get yourself a reputable reference guide for more information.  


  • A phototoxic essential oil means when it is applied topically the skin and you expose your skin to sunlight (this includes tanning beds), there is an adverse chemical reaction
  • Using these oils inappropriately could cause serious skin burns, and in some instances permanent discoloration to the skin (to see a photo, go to Moon Haven’s blog post – insert link:  
  • Read your skincare labels carefully

 And finally, I leave you with another piece of advice to keep your skin happy and healthy - if you are a fan of margaritas, especially lime ones, or enjoy a shot of tequila with lime – be careful getting lime juice on your lips!

Happy blending.



Robert Tisserand & Rodney Young (2013) Essential Oil Safety: A Guide for Health Care Professionals

Leave a comment