stylistic:tone, information:extraction, quality:correction, information:highlighting
Immunological; asthma and allergy

Evidence in peer-reviewed journals shows that some fragrances can cause asthmatic reactions in some individuals, especially those with severe or atopic asthma. Many fragrance ingredients can also cause headaches, allergic skin reactions or nausea.

In some cases, an excessive use of perfumes may cause allergic reactions of the skin. For instance, acetophenone, ethyl acetate and acetone while present in many perfumes, are also known or potential respiratory allergens. Nevertheless, this may be misleading, since the harm presented by many of these chemicals (either natural or synthetic) is dependent on environmental conditions and their concentrations in a perfume. For instance, linalool, which is listed as an irritant, causes skin irritation when it degrades to peroxides, however the use of antioxidants in perfumes or reduction in concentrations can prevent this. As well, the furanocoumarin present in natural extracts of grapefruit or celery can cause severe allergic reactions and increase sensitivity to ultraviolet radiation.

Some research on natural aromatics have shown that many contain compounds that cause skin irritation. However some studies, such as IFRA's research claim that opoponax is too dangerous to be used in perfumery, still lack scientific consensus. It is also true that sometimes inhalation alone can cause skin irritation.

A number of national and international surveys have identified balsam of Peru, often used in perfumes, as being in the "top five" allergens most commonly causing patch test reactions in people referred to dermatology clinics. A study in 2001 found that 3.8% of the general population patch tested was allergic to it. Many perfumes contain components identical to balsam of Peru.

Balsam of Peru is used as a marker for perfume allergy. Its presence in a cosmetic is denoted by the INCI term Myroxylon pereirae. Balsam of Peru has been banned by the International Fragrance Association since 1982 from use as a fragrance compound, but may be present as an extract or distillate in other products, where mandatory labelling is not required for usage of 0.4% or less.