Phototoxicity: Citrus Oils and Sunlight
Why some citrus and other oils can cause burns, blisters or dark patches when skin meets sunlight, which chemicals are involved, and what the FDA, a case series and lab studies say.
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If skin blisters, burns or turns dark after an oil and sun or tanning-bed exposure, see a clinician. A dermatology case report describes blisters appearing 48 to 72 hours after contact with bergamot oil and ultraviolet light. [1]
What phototoxicity means
A phototoxic reaction happens when a substance on the skin absorbs ultraviolet light and then injures the skin, like a sunburn that appears only where the substance was. NAHA, a US aromatherapy professional association, describes it this way: burning or skin pigmentation changes such as tanning, on exposure to sun or similar light, ranging from a mild color change to deep weeping burns. [2]
The US FDA says certain citrus oils used safely in food can be harmful in cosmetics, particularly when applied to skin exposed to the sun. [3]
Which chemicals are involved
A dermatology report on bergamot oil (from the rind of Citrus aurantium ssp. bergamia) says the oil has photosensitive and melanogenic (pigment-producing) properties because of furocoumarins, mainly bergapten, also called 5-methoxypsoralen. [1] Furocoumarins are the family of light-reactive compounds. Whether a particular bottle contains them depends on the oil and how it was made.
What the research found
| Question | What the source found | Evidence label |
|---|---|---|
| Can bergamot aromatherapy oil cause blisters? | Two patients developed localized and widespread blistering after bergamot oil and UV exposure. One had no direct contact: the patient was exposed to evaporated oil in a sauna and then UVA in a tanning salon. [1] | Case report (2 people) |
| Do bergamot oils differ between suppliers? | Of four supplier samples, two showed potential for photoactivation on chemical analysis; the lab test gave only borderline results and depended on the solvent. [4] | Laboratory study with a small human skin test |
| Are other citrus oils phototoxic? | A tiered test of orange, lemon and Litsea cubeba oils, following the bergamot study above, found phototoxicity depended on the content of photoactive components and the solvent. The abstract reports that 3 of 8 tested oils evoked a phototoxic reaction in volunteers at the highest concentration that was non-phototoxic in a skin model. [5] | Laboratory and small volunteer study |
The 2010 abstract does not say which of the eight oils reacted, so no single oil is blamed here. A 2001 report notes bergamot oil had been restricted or banned in most countries as an ingredient in cosmetics because of certain adverse effects. [1]
Pressed or distilled?
NAHA publishes lists that separate oils obtained by pressing the peel ("expressed") from steam-distilled versions. It lists expressed lemon, expressed lime, expressed bitter orange and bergamot among photosensitizers, and lists distilled lemon, distilled lime, sweet orange, mandarin and furanocoumarin-free bergamot under "non-phototoxic citrus oils." [2] It lists grapefruit as low risk. [2] This is one professional association's table; we found no regulator table in the sources we read, and the lab studies above did not compare pressed and distilled oils. See How Essential Oils Are Made.
Related cautions from the same sources
- NAHA advises that photosensitizing oils not be used or recommended before going into the sun or a tanning booth, with sun avoidance for at least 24 hours after skin application. [2] This is a professional association's guidance to its practitioners, not a regulator's rule.
- NAHA says certain drugs, such as tetracycline, increase skin photosensitivity. [2] Ask a pharmacist about your medicines. See Essential Oils and Medicines.
- Proper evidence not found in the sources we read for phototoxicity from diffused or inhaled oil alone, other than the sauna case above. [1]
Pages for specific oils
Bergamot, lemon, lime, grapefruit and orange oils each have their own guide. For other skin problems see Essential Oil Skin Reactions.
Frequently asked questions
Which oils are phototoxic?
Bergamot is the best documented in the sources we read. [1] NAHA's table also lists expressed lemon, lime and bitter orange, cumin, angelica root and rue. [2] Labels and botanical names matter; see Reading an Essential Oil Label.
Does it only happen in summer?
The sources describe exposure to sunlight or tanning-bed UV, not a season. [2][1]
Is a reaction an allergy?
Not necessarily. Phototoxicity is a chemical-plus-light injury, whereas allergy involves the immune system. [6][2]
Are citrus oils unsafe in food?
The FDA says certain citrus oils used safely in food can still be harmful in cosmetics. [3] We give no advice to swallow any essential oil.
Can sunscreen prevent it?
Proper evidence not found in the sources we read for this question. Ask a pharmacist or dermatologist.
References
- Accidental bullous phototoxic reactions to bergamot aromatherapy oil, Kaddu S, Kerl H, Wolf P, J Am Acad Dermatol 2001, PMID 11511848. Read 2026-10-23.
- Safety, National Association for Holistic Aromatherapy (NAHA, US professional association); page undated. Read 2026-10-23.
- Aromatherapy, US Food and Drug Administration, content current as of 09/08/2023. Read 2026-10-23.
- Phototoxicity of bergamot oil assessed by in vitro techniques in combination with human patch tests, Kejlová K et al., Toxicol In Vitro 2007, PMID 17669618. Read 2026-10-23.
- Phototoxicity of essential oils intended for cosmetic use, Kejlová K et al., Toxicol In Vitro 2010, PMID 20688147. Read 2026-10-23.
- Contact dermatitis, NHS (UK), page last reviewed 03 May 2023. Read 2026-10-23.