Phenergan (promethazine): I am on opiate pain medication for a back injury from a car accident, and the opiates make me nauseated and vomit. Pain doc put me on 25mg Promethazine 3X a day and it works wonders! It will make you a little sleepy, but once you get used to it then that feeling goes away. It does strongly 'clog' CYP3A4 nicely though, and although that's almost an 'auxillary' enzyme for alot of opiates, it definitely helps out. Again, it's cheap. Go to any grocery store and you should be able to get a nice big bottle of 100% whitre grapefruit juice from concentrate for like $2.50-$3.50. There are literally dozens of chemicals that can potentiate opiates, many with similar mechanisms. We will start with the most well-known ones slowly move into the more novel ones as we go down the list. Grapefruit Juice – The classic. Works by blocking the enzymes that metabolize opioids, thus increasing opiate concentration and duration. Opiates potentiation is the effort to increase opioid effects like analgesia. Several methods are used to induce potentiation, including drinking grapefruit juice and taking natural substances as well as mixing opioids with medications and other drugs. Opiate potentiation can be very dangerous. Personally I think anything that potentiate opiates is good. It keeps the tolerance lower and polydrug-abusing is much funnier anyway. When You get use to it You'll need so much of the gear to get off of it that it's almost no idea. People who needs Promethazine for allergy may use it constantly for maybe a half a year or more. I had a dozen or so phenergan's(promethazine), 25mg, on hand and has heard various reports on the net that they can potentiate the effects of opiates (swims on 90mg methadone daily). does anyone have experience combining phenergan w/ any opiate? results, positive, negative, none? if it does work well to potentiate opiates any dose suggestions? please help by responding peace. If I am right then D2 is supposed to be more stimulating (a typical anti-psychotic site), not as opiates. Furthermore, no functional person would have all of their D2 blocked - a drug only works on a portion of the nueron(s) it can affect. And finally, going along with this, promethazine and opiates work in different brain regions. Methods of Combining Opiates with Potentiators. Alternative methods of taking opiates can enhance the effects. For example, Antihistamine Aficionado states that when codeine, hydrocodone, oxycodone, or dihydrocodeine are ingested rectally, the effects can be increased by 10 percent. Combinations - does phenergan (promethazine) really potentiate opiates? Discussion in 'Opiates & Opioids' started by Stiffy, Oct 15. Promethazine does not have ANY effect whatsoever really beyond reducing the nausea aspect associated with an opiate. Promethazine mixes pretty well with opiates in my opinion. Promethazine – Any other sedative anticholinergic antihistamine will work to reduce opiate side effects and potentiate analgesia. Take after administration of opiate not before. CPM (Chlorpheniramine maleate) – Same as above. Cyclizine – Same as above. Anafranil –A Tricyclic antidepressant that could potentiate opiates.