Are you talking about "pure" NRIs or just those with significant NRI effects? If the former, then you're really talking about a tiny number of meds available in the US. If the latter, I've found plenty of meds with noradrenergic effects (TCAs, milnacipran and Sunosi, cymbalta, even effexor/pristiq) helpful for chronic pain (and some types of headaches). Atomoxetine also has decent evidence for treatment of anxiety, though I believe those studies looked specifically at people/CAP with ADHD with co-morbid anxiety disorders. That said, I have seen patients with who were convinced they had ADHD where I felt it was questionable report improvements in anxiety with atomoxetine even with minimal perceived effects on ADHD.
I have never heard of or used doxepin for ADHD, pain, or headaches.
Because the person I was asking was specifically saying they use atomoxetine for comorbidities, I was asking about pure NRIs.
I'm aware of all those SNRIs and their uses. Admittedly, never tried milnacipran nor levomilnacipran. Not because I don't trust them, but because I've never used them so I have no experience with them. I don't like to start Pristiq, but I've continued it for people.
Doxepin has a strong evidence base for pain. According to some studies, it's better than Elavil. I'd go for it for someone with ADHD symptoms, anxiety, and insomnia. I don't think there's much evidence for it in ADHD like there is for imipramine or desipramine, so I'd use it for someone who doesn't have OSA but has pain and insomnia that I think are majorly contributing to their executive dysfunction.
In my experience, I don't like to use the SNRIs for "ADHD patients" because they tend to inhibit cyp2d6 and the patients invariably don't respond well enough to avoid a stimulant. They also tend to be just as poorly if not worse tolerated than TCAs in my patients, and considerably less effective.
I've definitely had surprising results from chronic pain relief in patients with Cymbalta, and those patients say "my ADHD got better." Those tend to not be patients that I have diagnosed with ADHD, though.
In a possibly surprising reversal to some here, I do consider a UDS for chronic pain patients. I also universally don't prescribe controlled substances (other than gabapentinoids for neuropathic pain) to patients with chronic pain. I'm too concerned that it will lead to substance abuse problems. I refer them to pain management practices if they want a CS.
I do also want to clarify - anyone with a family history of substance abuse or who mentions a friend with substance problems would get a UDS from me. Anyone who says they tried a friend's Adderall and it helped doesn't get a stimulant from me. Anyone who drinks doesn't get one. We tend to trust patients words on the alcohol consumption, right? Or do others order labs to screen for alcohol use? Why's marijuana any different? IME, people who use marijuana can't help themselves from sharing that fact. People who use cocaine usually look like cocaine users.