The effect on your nails isn't going to be helped with a topical, this symptom is from a systemic issue. Not everyone with psoriasis gets the hair and nail symptoms. Diet might help, you can also try a hair and nail supplement. The itchy skin is different for everyone. While a cortisone cream can be helpful, there are so many other factors that effect psoriasis because it is an autoimmune disorder. For me cortisones only helps if I catch it right away, the biggest help is my diet, stress and skincare routine. This took me years to figure out and I am still learning new things. You could try elimination diets to dial in if your nutrition is a factor. Make sure you do your homework with this, you can effect your vitamin, mineral and electrolyte balance when you do this so being educated is crucial so you don't add a bunch more issues. If you have a holistic health store near you, they usually have someone who is very experienced that can help you navigate this. Some doctors want to start throwing medications at the problem right away, and though medications are necessary for some people, some can be controlled without. The medications that are prescribed for psoriasis usually entail stifling your immune system. Sorry so long winded.

I use Cortisone cream with vitamins A, D and E then use A&D ointment, baby oil, Vaseline or Vick’s over it. Anything thick that won’t irritate your skin. Also use Baby Magic lavender and chamomile wash and use it for hand washing too

Have never found something that works on nails- I'd love to hear this answer!

I use Gold bond lotion for psoriasis. Seems to clear up my skin.

I use cortizone 10 and/ or antibiotic ointment. Lotion with cocoa shea butter in it right after a shower to help w psoriasis. Hopefully you find something that works for you.