Hi @ChraK60,
I know soap being high pH dries my skin excessively. I use moisturising cream is place of soap.
High BSLS also can cause itch and increase the risk of fungal infection of the dry skin, e.g. dandruff scalp and other skin flaking.
Things are much better for me with normal BSLs and use of tar-based creams with a weekly anti-fungal treatment ( e.g. selenium-based shampoo). Because I get itchy skin in the dry winter air occasionally I am prescribed a low dose steroid cream but only if there is no active fungal infection.
Someone laying on their back in bed particularly with say plastic underlay may cause excessive sweating, --> wet, dry cycle which exacerbates risk of fungal infection.
Could any medication be increasing the risk of itch?
And some vitamin and mineral deficiencies are associated with skin problems. I have mentioned vitamin D and zinc below but Vitamin A, B2,3,5,6, 7, vitamin E and calcium can be causes as many websites will say. Of course, check with your doctor before adding in foods and supplements as excesses of say Vitamin A, D, B6 etc can cause problems.
And as well as external application of creams etc, I add linseed powder, and when I can obtain it, a mixture of powdered LSA (linseed/safflower/almond) to my breakfast cereal as the oils in them appear to work 'from the inside'. Omega 3 fatty acids contained in these seed/powders are important for good skin.
I am unsure whether vitamin D supplements are warranted during summertime but even here in sunny Australia during winter many elderly people suffer from vitamin D deficiency. Dry skin is one symptom but also bone health is a big deal here and some say they are less prone to colds etc during winter if they take Vitamin D supplements. Something to ask her doctor about.
One thing my doctor did was to ask me to taste a solution of a zinc compound in water. Apparently, if you cannot taste the zinc, you are low in zinc in your body. ( he said that if you are replete with zinc you can taste it and are less likely to eat foods that contain much zinc due to the taste. On the other hand if you are low in zinc you can tolerate food with more zinc in it because there is no taste experienced to put you off eating much of that food). Zinc apparently is important for skin health. It may be that the zinc in many protein foods is one of the reasons protein intake helps skin health.
I hope the above helps as at age of 92 I imagine any irritant is a source of unhappiness !!