I am pretty sure that 20mg of methadone isn't going to kill you, even if you are opiate naïve, just so long as it was JUST methadone you took, mixing methadone with other CNS depressants like opiatekrzy said, is potentially extremely dangerous, especially to someone opiate naïve such as your self.. and yeah so your not itchy? that doesn't mean it is fake, not every opioid is going to make you itch, yes it may sometimes and some will more than others, but its not like if your not itchy its a complete deal breaker and totally a fake pill! lol. It should make you feel sleepy/sedated, especially if your opiate naïve, basically like your nodding in and out of consciousness! that is entirely normal, not to say they couldn't possibly be fake, its just, not too likely they are. I have yet to hear of a fake methadone pill, though I am sure some asshole made them and they are out there, using something like fentanyl instead of methadone, but if it was laced with fentanyl you would most likely be overdosing right now, or had already OD'ed and died, because if fentanyl falls into the hands of someone opiate naïve, they are most likely going to OD and the outcome most likely will be death if too much is consumed, which in the case of fake fentanyl knock off pills, they usually put ALOT of fent in them, from what I have heard! Most of the time people only make the more "popular" pills and street drugs, with fentanyl or just with something like chalk, or some totally inactive ingredient... Oxys, Roxys, Xanax bars, pills like that, are usually the most likely to be fake, and that when purchasing off the street or dark net(especially the dark net!) you should definitely be wary of them.. i don't think you need to worry though in all honesty.. just don't take any more than you already have, and if you do don't take too much more, maybe like 10mg tops.. if you must.. since your opiate naïve, i would still say don't bother as your probably as nice as you want to be right now, and shouldn't risk a possible OD. And check out the imprint on the pills, using a website or google that identifies all prescription or OTC pills, and their size, shape, color, and imprint, there are a few good sites out there.. just to make sure. Be safe, and i wouldn't make it a habit of taking opioids, if i were you! it is one hell of an addiction, literally, once you get physically dependent, and methadone is by far one of the worst of them to withdraw from, due to its long half life/duration of action, and it being a powerful full agonist opioid. Be safe!