Let's start with things that don't work:
DXM - You would think any kind of anaesthetizing chemical would help, and DXM is over the counter, I mean, it couldn't hurt, right? It'll make you feel like your head is a helium balloon, and you'll still feel all of the negative effects of PAWS, plus more nausea. Bad idea. In desperation, I took 150mg, and it basically ruined half my day (as if it couldn't get any worse).
Recreational Stimulants - Ecstasy makes you feel worse. So does speed. I'm sure some people will tell you otherwise, but even if it did help temporarily, the crash will be magnified times a jillion. It's just not worth it. The bad feelings from PAWS don't go away. They just sit alongside all the stimulation and scatterbrain-ing.
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Let's finish with what does work. This has been my regimen:
Naproxen (Aleve) - For muscle cramps, helps a little. Take two or three twice a day.
Ranitidine (Zantac) - This pill will help all your stomach related issues, save for vomiting. When I've withdrawn from tramadol, I get incredibly awful stomach cramps from stomach acid, bordering on peptic ulcer status. I was at work once during PAWS, and I was having trouble standing from the pain and cramps. I took two Zantac, and it made all the difference. I was pretty shocked.
Loperamide (Immodium) - I've never felt its peripheral opiate effects (they say it's supposed to help you feel a little better in general, supposedly), but it definitely helps with the diarrhea. I still take beyond the recommended dosage; I'd rather be constipated for a few days than having to run to the bathroom every thirty minutes. Does anyone know at what dosage it helps with peripheral withdrawal effects? I mean, I thought it might have helped a little at 10mg, but it might have just been placebo.
Benzodiazepines (Xanax, etc.) / Carisoprodol (Soma) - This is optional, but it really does negate a huge percentage of the dysphoric effects of PAWS, so it's really almost essential. It will help you sleep at night, and help you relax during the day. The worst of PAWS really only lasts two or three days; after that, you don't really need the benzos. It's not enough time to worry about addiction; you just have to remember to cut yourself off after a few days. If benzos aren't available, and for a lot of people they aren't, carisoprodol (Soma) is much more readily available (unscheduled in most places, available OTC in a few, and you can order it online pretty easily everywhere else) and it's not a bad substitute.
Ensure - Good healthy smoothies that substitute for meals. Good if you can't eat.
Gatorade - For fluids.
Some hilarious DVDs to watch - Comedy heals the soul.
Energy drinks - Usually okay after the first day or two; be careful drinking them too close to bed time, or you'll have a hell of a time getting any sleep. This isn't as big of an issue if you have benzos or Soma. In fact, the caffeine will negate some of the hypnotic effects of the depressants during the day, while leaving the anxiolytic effects (what you want primarily). DON'T go overboard. I only have used a lot of caffeine when I really cannot take off a few days and have work to do. If you can manage without caffeine, it's for the best.
If all else fails, I usually write the words "I'm okay!" along with a happy face on the palms of my hands with an indelible black marker the day before withdrawals. If things get bad, just look at your hands: it's your non-PAWS self reminding you that things will be better soon. I know it sounds a little silly, but to me, it's levitated me out of the worst of lows during PAWS.
As a side-note, I only have experience withdrawing from prescription opiates, primarily tramadol. So I can't speak for everyone with my post, but tramadol is known to have some of the worst withdrawals of all opiates, at least in terms of mental anguish, so I can speak with a modicum of experience behind me.