Can we skip a treatment when side effects to much.?

From experience can anyone please tell me if we can front up to our onc treatment day and request a reprieve from the drugs? Seriously I'm now on a break and it's lovely however would be if I wasn't itching and burning all day and night as a drug skin reaction.  Nothing helps and I'm definitely sure my low feelings of late are due to lack of sleep and this . So I'm wondering if I can have a break providing bloods are  all good of course . I am on herceptin and perjeta and due in a week .