Anyone can die from dehydration, whether or not they are in withdrawal or not if they get a dose of the shits! In my entire career I have never seen anyone die of withdrawals. I have seen many people die from overdose.
When we are talking about deaths directly attributable to withdrawals we have to talk about things like respiratory depression, seizures etc. Opiate withdrawals are very unlikely to cause these symptoms, unlike alcohol and benzos.
I don't think it is helpful to people who are trying to reduce of small amounts of codeine these scare stories. It is not unsafe to reduce off these medications, thousands of people do it every single year without too much bother. Lots of people will be taking dihydrocodeine or other pain relief following surgical intervention, and they reduce of them with no help. Why? Because psychologically they expect to be able to do it. The few people who get stuck on low doses may need reassurance that they are not going to suffer unduly from withdrawal and they can do it safely.
Yes, if you are taking high levels of Neurofen Plus, the most risky drug in that is the Neurofen, and you might need to check out with your GP that you haven't fucked your stomach lining.
Yes, if you are taking co-codamol, you need to check that you haven't fucked your liver with the paracetamol.
The codeine, ironically, is the safest part of both of these drugs and yet people get head-fucked at the idea of reducing them.
Reduction off low levels (and high levels) of codeine is possible without medical intervention. A slow reducing dose, with some confidence that it is do-able is what is needed.
I am not minimising people's concerns... I am just saying I spend every single day of my working life discussing these things with clients, and encouraging them to be optimistic about their capabilities.
So, OP. You've got this! Be confident that you are likely to be through the worst, You can be confident that due to the half life of codeine the whole dose will have left your system in 16 hours and you you can expect any withdrawals to peak at about 24 hours and then improve and reduce. The physical withdrawals will ease, you need to find ways to manage your head. Good luck x