Is a shampoo bar okay for people with hair loss?

Lately, it feels like I'm suddenly losing 300 to 400 strands of hair a day. A lot falls out even when I wash my hair. When I walk, hair falls down onto my clothes and my back. I wasn't worried because I have thick hair, but I'm concerned because the loss is so severe. With a shampoo bar...

I'm wondering if it's okay to wash my hair. I am worried that the surfactants in the soap might accelerate hair loss. I have a friend who is currently experiencing alopecia areata, and I are wondering if it would be okay for us to use shampoo bars?