When people ask me personally what the best medications are for treating Opioid withdrawal, I generally say these three:
Clonidine (Catapres)
Gabapenting (Neurontin)
Marijuana (The Dankies HCL)
Just an aside, for many folks, the get recommended sedative antihistamines like Diphenhydramine (Benadryl), which would seem alright, but in practice, these often exacerbate symptoms like Restless Legs and I can personally attest to this. If you're going to take an antihistamine, Hydroxyzine (Vistaril; Atarax) is a lot better in this regard and has many of the same benefits that Diphenhydramine would have.
Clonidine should be taken a few times a day, 0.2mg each, although some people in severe withdrawal can tolerate 0.3mg. Start slowly. The primary side effect of overdose is going to be orthostatic hypotension and hypotension in general. At any rate, if you're new to Clonidine, be careful getting up too quickly as a lot of folks experience syncope from too high a dose. Clonidine is helpful in reducing temperature issues (heat/cold intolerance), perspiration etc. It helps with anxiety in a more physical sense. It will make you feel less on edge/tight in the chest. It's most useful for insomnia in my opinion.
Gabapentin (Neurontin) I would say, take 300mg every 30-45 minutes with food (important) until you feel okay. You shouldn't be taking more than about 1800mg without a previous tolerance, but it's not a drug that causes problems for most people in elevated dosages. It's prescribed in dosages as high as 4,800mg a day safely. Gabapentin helps a lot with Restless Legs/Akathisia, Insomnia, Anxiety and Insomnia. In my personal opinion, the most effective drug for treating Opioid withdrawal that isn't an Opioid.
Cannabis is just helpful for symptoms like nausea, insomnia and anxiety.