there are a number of homeopathic meds. your local pharmacy is the source. ask the pharmacist. my wife uses melatonin. sometimes a single benadryl will make you sleepy.
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The closest to ambien is a drug called doxylamine succinate. It is marketed under the brand name Unisom. If you buy it make sure to check the box to see if it is the doxylamine because Unisom also has a diphenhydramine formulation. This drug has been shown to be as or more effective as many popular sleeping meds and it is not habit forming.
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I frankly did not like the way I felt after taking Ambien especially if I took it two nights in a row.
As far as over the counter, try two caplets of diphenhydramine, which is over the counter. Also the next time you are at your doctor ask for something to have on hand that is non addictive. Something like Tizanidine it a muscle relaxer but also is very helpful for getting a good nights sleep. Be careful about depending on aids to much. Try not to get on the computer right before bed. No working out. I try not to sleep with the TV on but at times I forget. God Bless Reggie
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26+ yrs counselor

If you don’t take Ambien, Unisom is the way to go. Sometimes if I’m out of Ambien or don’t feel like taking it, and my allergies are bothering me, I’ll take a Benadryl and that really relaxes me and I get sleepy within half an hour. I’ve taken Ambien for years….you can check out my experiences on my blog if you want. (Ambien Nights)
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http://ambiennights.blogspot.com/

Try http://insomnia-sleeplessness.blogspot.com/
It will help you a lot, and for free.
References :
http://insomnia-sleeplessness.blogspot.com/