These are some of the oils that can cause sensitization:
- basil (French)
- bay laurel
- benzoin (unless specified as skin-safe)
- cedarwood
- chamomile (both Roman and German)(pretty rare)
- citronella
- garlic
- geranium
- ginger
- jasmine
- lemon
- lemongrass
- litsea cubea
- mints
- orange
- Peru balsam
- pine needle
- tea tree
- thyme (white)
- vanilla
- turmeric
- valerian
- violet
- ylang ylang
- Make sure you know your ingredients - if you're including an essential oil in your soaps or other products, make sure you know about its recommended usage and possible sensitization issues.
- Make sure your oils are fresh. Many oils, most notably pine/evergreen oils and citrus oils, will become more sensitizing as they become older. The oils oxidize in the bottle and develop compounds that cause the sensitization. You can prevent this by adding a bit of rosemary oleoresin extract to the essential oil - or just make sure your oils are fresh.
- Test them before you use them - be sure to do a small skin test with an essential oil before you use it all over your body - especially if you, or the person using it, are prone to allergic reactions.
- Label everything clearly - most people who are allergic to compounds know it - they've been dealing with sensitivity issues all their lives, so they know to be on the lookout for certain chemicals or compounds. But they can't stay away from something if you don't tell them it's there, which is why proper labeling of all of your soap and other products is vital.
- Alternate your oils. Don't use a sensitizing oil in every single essential oil blend you create. Alternate them. Don't use a product containing the same essential oil every day. (That even goes for "safe" essential oils like lavender.)


