Sun is not the only thing that causes discolouration, inflammation (wounds, skin problems) can also leave behind discolourations. Some women get discoloured patches after pregnancy. However there are many other things that can cause hyperpigmentation or worsen existing discolourations: problems with the liver or adrenals, vitamin deficiencies, medication.
If your skin tends towards discolourations you need a dual approach: good cosmetic routine to deal with it is essential, but you also need to look into what caused or triggered the problem. Some of the triggers are hard to avoid, sometimes we don't have much choice when it comes to certain medications, birth control or other issues, in this case we should try minimise other potential triggers of hyperpigmentation. And wear lots of sunscreen. And hey, if nothing works out, that's what make-up is for.
What May Trigger Hyperpigmentation:
* UV rays, especially tanning beds which use mostly UVA light. Also the UV gel hardener lamps.
* Incorrect use of sunscreen: sunscreen that isn't full-spectrum, too low SPF factor, isn't applied correctly (a thick enough layer, patted on and not rubbed on), chemical sunscreen that isn't applied 20 minutes before sun exposure and reapplied every two hours. Obviously all of this doesn't trigger melanin production per se, however when we apply sunscreen we tend to spend more time in the sun -- even if the sunscreen doesn't offer enough protection.
* Adrenal stress
* Liver problems
* Essential oils: bergamot, lemon, lime, orange, mandarin, juniper, jasmine absolute, lavender, red zig, sandalwood oil, ylang ylang oil.
* Antibacterial/antiseptic ingredients (soaps, cleansers, household cleansers): Hexachlorophene, bithionol, 5-bromo-4-chlorsalicyanilide, chlorhexidine, chloro-2phenyphenol, triclocaran. More reasons anti-bacterial stuff is ineffective and bad for health anyway.
* Perfume, also synthetic fragrance in skin care: Peru balsam, benzoyl alcohol, benzoyl salicylate, canga oil, cinnamic alcohol, geraniol, hydroxycitronellal, mithoxycitronellal, oak moss, musk, xylol, 6-methyl coumarin, cinnamic aldehyde. Unfortunately these do not have to be disclosed and are often simply declared under inci: parfum.
* Deficiency in vitamin B12 and other B vitamins, vit A, vit PP and folic acid.
* Hormones: this includes birth control as well as pregnancy.
* Improper used of hydroxy acids: A lot of anti-ageing, brightening and anti-acne products contain AHA and BHA, which make the skin more susceptible to UV rays. I've even seen them in sunscreen. Always use products with these ingredients in the winter, apply only in the evening, and use proper sun protection!
* Some herbs: fennel, calendula, St John's Wort, figs, lime, parsley and wild carrots.
* Many medicaments: antibiotics, anti-inflammatory anti-fungal agents, some blood pressure medication and pain killers. One list and another list, also a good list. If you are on any of these any cannot switch, take extra care with sunscreen!
* Acne medication: Benzoyl peroxide, retinoic acid, unbuffered and very low or high pH glycolic acid, tretinoin, resorcinol.
* Systemic drugs: Tiaprofenic acid, carprofen, promethazine, chloropromazine.
* Sunscreen chemicals: Para-aminobenzoic acid, glyceryl-paminobenzoate, 2-hydroxy-4-methoxy-benophenone, isoamyl-p-N, Ndimethylaminobenzoate, p-methoxy-isoamyl-cinnamate. Or basically: switch to zinc oxide based sunscreen already.
* Other cosmetic ingredients that are photosensitising: hydroquinine (brightening products), retinol (anti-aging).
I hope that this list is helpful. It's definitively not completely exhaustive, it was really surprising how little information there is out there on photosensitising cosmetics ingredients. When in doubt, wear sunscreen!
Photo credit: Mohammad Metri on Unsplash