It's not worse than IV heroin in terms of withdrawal. Cold turkey IV heroin withdrawal was the only opioid withdrawal I experienced where I experienced open-eye hallucinations. I'm not talking subtle visual disturbances but full on immersive psychosis-like states, I looked at the sky and the clouds turned into a three headed dragon, followed by loss of reality/time. I remember seeing stuff like that in movies like Trainspotting and always thought that it was theatrical bullshit till I actually experienced it.
Tianeptine withdrawal doesn't compare to that, but it is pretty miserable. I'd liken it to a less intense version of oxycodone withdrawal (which is awful), but with the big benefit of the acute stage being significantly shorter. The acute symptoms are pretty much done by day 4-5. I mean you still feel bad, but the worst of the storm is over.
That said, tianeptine is extremely addictive, and once you start taking it alot, withdrawal symptoms start appearing only 3-4 hours after dosing.
Is she taking tianeptine powder? For someone not accustomed to opioid withdrawal, tianeptine withdrawal can easily feel like the worst thing they've experienced