My doctor has put me on sertraline.

My personal advice is to ask for Anti-Anxiety meds. Anti-depressants are NOT the same. It's frustrating to me that this mis-diagnostic exists with its inappropriate prescription error. These individuals could get sued. 

Other than the flu, vomiting is usually a gravely serious sign. 

Depression can be due to the body shutting down and preparing to embrace death (can be positive after a very long life), It can be a sign of a serious illness, it can be a sign of a lack of vitamins / nutrients, it can be a sign of an imbalance in our hormones. 

Anxiety is not caused by these factors, though it can be caused by low blood sugar/pressure and other health issues, but it isn't an imbalance and in a majority of cases a state of being overwhelmed. It is also a state of being in a hyper-drive in the brain (when one is too excited before bed). For autistics, we are Deeply Impacted by our senses. We need mentorship, therapists, and resources to help us break down and understand and FIX things causing us anxiety. for instance, unnatural lighting, with it's high speed flickering will give me low-gads anxiety. Too much caffeine plus extra vitamin D will give me anxiety. Unresolved anger / frustration when I do not have the understanding of the situation, the identification of everything happening, the roles and responsibilities of others, can bring about anxiety. Working until 2 am automatically causes anxiety. The only way I can sleep is with a micro-dose of Xanax, which is a powerful drug, but since I'm mindful about it, I don't ever take it more than 3 days in a row. And make sure I use it to help me focus or just work through whatever issue I need to discover resolve with. The world is anxiety-inducing. 

I would personally suggest you do a bit of research on the difference between depression and anxiety, evaluate your diet (maybe you could use a multi-vitamin for balance), and write down specifically all the key things you're having difficulty with. Write a letter to your GP if feel like you've been misdiagnosed (I would use this word), and explain you need help to stay focused, to stay healthy but need help with anxiety NOT depression. Ask for a therapist as well as a small dose of anti anxiety medication. Beware they may give you a sugar pill, and make sure to report if it doesn't work.  Autistics need help with how deeply we are impacted and I am genuinely putting this on my list of things to fix and advocate against. x

I have used it.
I didn’t sleep on day 1 for 24 hours! It was awful. Early symptoms included dizziness, nausea and headaches and it increased my anxiety in the first 2 months

I didn’t actually feel any positive effects until week 12 or 13, by which time my anxiety levels had really reduced. I felt very calm as well.

I always took mine with a plain biscuit and half a glass of water. That way I found I had less nausea.

The shorter the time period you are on it, the better. I was on it for 2 years, then I tapered off very,  very slowly over several months and had virtually nil withdrawal side effects. So much so, I had started a new job at the same time, and my husband has just left me, and I was absolutely fine!

I was on it for a time. I was told that it takes 6 weeks to really start to work properly, and that anxiety can be worsened by it in the meantime. I found that to be the case for me, but not everyone's the same. I did get some anxiety relief after a while but became resistant over time so it came back and all I was left with were the side effects of  (in my case) jumping limbs and significant weight gain. A lot of others seem to to have more postive experiences, and other '...ines' exist to try as alternatives too. I did Sertraline, Venlaxafine, and one other I've forgotten the name of. The first phase got me through some extremely difficult times (not that things are much better, I'm just more inured to dealing with ongoing painful emotional fallout), but the eventual switch in positives to negatives ratio was for me a clear sign to come offf them. 

I think some autistic people don't get the benefits from these things that NTs do - they may take the edge off slightly but we're just too wired for worry not for it to break through.