Switching from sema to zep is often a pretty smooth ride. They're similar, but zep targets both GIP and GLP-1 receptors, so some people notice better appetite control. But, the initial side effects can be a bit stronger, like nausea and tiredness. Start with the lowest dose and increase it slowly, even if you feel okay at first.
Also, watch your electrolytes! Especially if you're eating less and drinking more water to combat nausea. Sodium, magnesium, and potassium are key. I've been using electrolyte drops in my drinks, and it's helped a lot with the fatigue and headaches. Give it about a month or so before you decide if zepbound is working for you – your body needs time to adjust.