Risk factors for PIH
Not only the Sun is to be considered responsible of the PIH, because the use of sun beds and exposure to similar sources of ultraviolet light will produce similar effects too.
And there is also inflammation in the skin, meaning that a number of chemical agents which intervene on the inflammation must be present in the skin while there is Sun exposure.
So, what will trigger PIH is a complex combination of skin injury plus Sun exposure plus chemical compounds from inflammation.
PIH frequently relapses, and the reason for this frequent repetition of the hyperpigmentation is because the melanocytes have already been stimulated to produce excessive melanin, the so-called hyperactive melanocytes, so they are prone to react similarly when exposed to similar stimulating factors, hence a relapsing hyperpigmentation.
Prevention of relapses by avoiding the triggering factors:
- Avoid Sun exposure. Daily use of a sun blocker with a protection factor of +50 with physical particles, and it must be renewed every 4 hours if you are in a very sunny area.
- Avoid heat exposure. No sauna, steam rooms, or other sources of extreme heat. This might be an issue if working in an environment with extreme heat, as a professional kitchen for example.
- Avoid any other sources of ultraviolet light. No sun beds.
- For how long? Well, as much as possible (even for good), because it will relapse otherwise.
Look out for unexpected ways of having Sun exposure
Along the years I learnt from my patients that there are many forms of being exposed to the Sun without using Sun beds or going to the beach on sunny holidays.
For example, I learnt that driving, or travelling on a train, might end up in an unnoticed sun exposure. This is the case if you have a 30 minutes journey back home on a train, or driving, immediately after receiving a facial treatment with laser, derma-abrasion, peeling, or micro-needling. In all cases, the skin is vulnerable to any sun exposure after the mentioned procedures.
Heat as a cause of postinflammatory hyperpigmentation
From several patients I
also observed that any sources of extreme heat must be avoided after any
facial procedure or treatment.
Sources of extreme heat include sauna, steam-rooms (I had a patient in UK,with a reluctant to treatment PIH, who finally told me she was going weekly to a sauna, a place where temperature might rise up to 70 degrees centigrade), and not to forget any source of heat from occupational environment, as working in a professional kitchen, or a laundry (I also had a patient in Spain, with a reluctant to treatment PIH, who finally told me she was a professional cooker working in an industrial kitchen, where usually temperatures are extremely hot).
I have to say that I have not found any sources or bibliographic references about this triggering factor for PIH (extreme heat), which according to my statistic is not very frequent (only 2 cases recorded in my experience), but I think it is a real risk factor.