Unfortunately, some people have the misconception that poppy tea is safe or less serious than other opiates simply because it comes from poppy seeds. However, this really isn't true. The seeds actually have a mix of morphine and codeine, along with other more minor alkaloids. So, it's basically multiple drugs in one, and the dosages can actually be quite high if you take enough. The amount of alkaloids in the seeds is highly variable, so it's important to start with a low dose (e.g. 80g or so) to determine if you want more or not.
You can absolutely overdose on the stuff if you take too much, just like any opiate. From what I have heard, the high is often very intense if you have no tolerance built up to opiates. The unfortunate issue is that it's addictive in a way that's a little different than most opiates. The high doesn't create much of a "rush" per say on the come up by comparison. So, it seems like it's relatively mild by comparison to other faster-acting opiates. However, the total dosage of alkaloids can actually be really high, and there's multiple types of them in the seeds.
So, the withdrawals are notoriously rough. Plus, the fact that they're cheap and easily available makes it all too easy to keep upping the dosage, which obviously contributes to addiction and could even lead to overdose. It isn't on the level of heroin use of course, but it's comparable to or worse than many/most pills. In addition to the horrid withdrawals from becoming a regular user, the difference in potency between batches can increase the overdose risk. Though, the fact that it's taken orally and that you can (and should) sip it rather than guzzling large amounts at once lowers this danger.
Still, it's not the relatively benign and harmless natural alternative to conventional opiates that some people think it is. So, it isn't a good idea to try to use it as a way to quit a pill habit or anything like that. You most likely will just end up switching addictions. If one is an IV drug user, drinking poppy tea can be a much less dangerous alternative to one's DOC. It's still highly addictive, causes horrendous withdrawals, and it's very possible to overdose on it like any opiate. Though, the risk of overdosing and dying is far lower than slamming dope obviously.
Relatively few people actually end up drinking enough of it to actually overdose and die, but it does happen enough to warrant serious caution with the dosage like any other opiate. Furthermore, many people on here have said that the taste of the stuff is absolutely and utterly vile. So, getting addicted to it and having to drink the stuff all the time to avoid withdrawal symptoms is an absolutely fucking miserable experience. It's essentially the Benzedrex of opiates. Obviously, it's completely different than that, but they both have the same sort of "shitty, yet addictive drug that probably won't actually end up killing you or anything" quality to them. Kratom is actually a safer alternative to opiates though.