Cosmetics may not infect consumers. Therefore they must be preserved. Ain insufficiently protected preparation which might spoil can irritate the skin through the metabolic by-products of microbes. In addition, the destructive materials can release derivatives which are not tolerated by the skin. The correct preservative is a compromise between effectiveness and side-effects. It should prevent microbial multiplication, but kill as few skin-protecting natural bacteria as possible. It must be toxicologically safe, may also produce no skin irritation or cause allergies, should in addition be tolerated by other ingredients, remain stable and not smell bad. A problem for the many synthetic preservative materials is that they have the potential to cause allergies. Formaldehyde releasers such as bronopol, DMDM-hydantoin or isothiazolinone belong to these materials. Preservatives are unfortunately not free of side-effects. They are substances which kill bacteria and also cause metabolic effects in the skin cells. Critics of plant oils say that in comparison to mineral oils, they can become rancid and therefore must be stabilized. But the use of natural and biologically degradable ingredients have the disadvantage to be made stable (for shelf life) with dangerous materials, but this argument is less convincing. Especially those products with mineral oils are for the most part filled with strong preservative materials. For cosmetics, plant oils are also recommended with a high amount of saturated fatty acids which have much better shelf life than oils with a high share of multiple unsaturated fatty acids. Avocado and jojoba oils are products from nature which are well conserved. Neither becomes rancid. Similar to the surfactants and emulsifiers, the development of cleaner preservative materials and systems has become very important. Important contributions have been made in the choice of raw materials, the manufacturing procedures and the methods of packaging. If the raw materials used are low or completely free of germs, the whole product does not require strong preservative measures. Significant for the type and amount of the material employed is the use of hygienic manufacturing. Packaging which assures that e. g. a crème will not come in contact with the fingers will reduce the necessity to add more preservatives to the product. A natural alternative to synthetic preservatives are, for example alcohols or specific etheric oils. The so-called natural materials such as sorbin or benzoic acid are also less problematic. They are found in nature, but are not naturally made – rather, they are synthetically derived. In some cases, also co-emulsifiers such as sodium lauroyl lactylate or glyceryl caprylate are used as preservatives. "Contains no preservatives." That is the most frequent confusing formulation, because at the least all aqueous products are made to last either through a preservative system or a preservative material. Mostly this means that this formulation is free from the preservatives listed in the cosmetic regulations. Materials which do not apply as preservatives which have other goals than preservation but have preservative characteristics, for example pentylene glycol. A product with pentylene glycol can be described as free of preservative materials. "Contains no synthetic preservatives." This formulation is more exact. Whichever material is used, one should ask the manufacturer about allergic sensitivity. Preservatives can, for example be contained in the perfumes.

Preservative, an important component of cosmetic products. As with foodstuffs, is in any case difficult to bring the bactericidal, disinfecting effect of the preservative with skin health and/or healthy digestion into harmony. Cosmetics may not however contain disease-causing agents. It is therefore not to be argued that the manufactures are obligated to prevent bacterial growth in their products, so that no health-damaging effects are produced. They are also obligated not to produce skin reactions or allergies which may be caused by the preservative, disinfective, bactericidal and antimicrobial ingredients. And therefore the significant frustration which has been brought if one sees the arsenal of highly reactive preservatives which are allowed to be added to cosmetics. Whether dermatologists and allergists assume billions of Euros for damage to health, and scientific committees in the EU speak of high allergic potential, preservative materials such as triclosan and methylbromo glutaronitriles are being used often as cosmetic ingredients. The pressure to preserve depends in part on the multiplicity of the types of cosmetic products. The always growing products offered on the basis of aqueous solutions and emulsions pressures the industry to conduct an ever-intensifying struggle against bacteria, germs, fungi and other such organisms. One piece of olive or seed soap essentially protects itself, while an ever-larger number of water-fat emulsions try to bring special protection, at least in industrially-manufactured shampoos, crèmes or bath salts with a shelf life of at least 30 months. Natural cosmetics show that with greater care for the reception and choice of raw materials, at least the hard synthetic preservative materials such as the chloraniline constructor triclocaraban and triclosan as well as the further disputed materials of the chlorine family such as methylchloroisothiazolinones, chloracetamide, chlorobutanol, chlorophone, p-chlorphenol, methylbromo glutaronitrile, iodopropynyl butylcarbamate, 2-2(3-heptyl-4-methyl-2-thiazoline-2-yliden)-methene-3-heptyl-4-methyl thiazolinum iodide (quaternium-73) or formaldehyde and their derivatives imidazoldinyl-uric acid, 5-bromo-5-nitro-1,3-dioxane, 2-bromo-2-nitropropane-1,3-diol, 3-dioxane, dizolidinyl urea (urine), DMDM hydantoin etc. can be avoided. It is more difficult to avoid preservatives with food approval such as the parabenes, sorbic acid, benzoic acid and its salts, the sorbates and benzoates. They are without question better tolerated because they all are found in nature, even if today they are completely synthetically produced. Despite this, one cannot exclude the possibility of allergic reactions with these materials. With the parabenes one can come to the realization that they have been tested in many animal studies in order to rule out the suspicion of hormonal effects. Carefully compare the products with this substance.

Substances which are used for the preservation against microbially susceptible salve ingredients. Preservatives are often contact allergens (cation CG at 4%, benzalkonoium chloride, thiomersal and parabene, each at 2%), so that one should seek, wherever possible, not to use a preservative.

Material must be used in combination, because due to its chemically similar characteristics within a group (group allergy) or with chemically different structures (cross-allergies), can cause cross reactions.