The important thing to keep in mind here is not necessarily the effect after a single dose, regardless of the amount of that dose, but the cumulative effect of multiple doses of meph on its own and, especially!, when combined with other substances. On their own, those other substances may not have a lasting or signifficant ill effect. Meph, however, is an immunosuppressant. As such, where you would not have suffered an ill effect from another substance before, once your body's defences have been compromised by meph, you may now see ill effects compounded, exponentially. What you may end up dealing with, in the end, is a recovery process not for meph, per se, but for any number of other substances which you may have consumed before, during, or after your meph consumption.
If you're consuming other substances, either before, during or after meph, then think of it as if you're consuming ten times the amount of those other substances, in terms of toxic residuals in your system. Not the "high effects", but toxic residue. There's a difference. So, for instance, if you're having a double shot of vodka after having some meph (a couple of days ago even), picture your liver under the stress of having twenty shots of vodka instead and imagine the relief and recovery you'd need to give it after such a stress. Same with other substances.
A quick appeal to members and mods here, if I may, please. The "idiots" and "retards" references about users and possibly abusers of meph is not helpful. Not on a board like Bluelight. The best path to harm reduction is not going to be paved with derision. No, those types of cobblestones won't stick; that path will not be chosen and travelled by those whom you wish to teach. The education on the chemical breakdown of meph has been phenomenal here. Time to take the lead in simple-language education about the possible harmful effects of this substance. Repetition, properly grouped reference material of experiences, so on. Not sure what the winning formula will be here, but the way to get there wouldn't be through name calling. Just my opinion.
Ill effects: if you notice skin changes, I would quit using all substances immediately! Urticaria, discolouration, sensory differences are all urgent signs that either your cardio, circulatory, liver and/or immune functions are critically compromised (short or long term). I would see a doctor for immediate check up, but be careful if they prescribe anything, because those prescriptions may compound the problem and create a host of other problems, now that your system has already been compromised. Seriously look into detoxifying your body in a natural way - lots of natural juice, lots of water, lots of other natural ways out there. Don't even think of exposing your body to anything toxic again until you've fully recovered.
If you're on SSRI antidepressants, I would think doubly carefully about going anywhere near meph.
I don't think I've ever cautioned, publicly, on the use of any substance before. This stuff, however, is cunning. It's like a trojan, where it may not do the harm itself, but will compromise your defences enough for any and all other substances to pose cumulative harm.
Stay safe!