Sorry man I was high as fuck when I wrote that but you should read the internet more if it's the most ignorant thing you've read or not the internet is a silly place but here is what i was talking about.

https://www.erowid.org/chemicals/mdma/mdma_neurotoxicity1.shtml

"It has also been suggested that some of the dopamine released by MDMA may be transported by SERT into serotonergic axons (Faraj, 1994) and subsequently oxidized (Nash 1990; Schmidt, 1990; Sprague and Nichols 1995b). The oxidation of dopamine can form hydrogen peroxide which, in turn, may produce hydroxyl radicals. A quinone-like dopamine metabolite may also be formed with potential to generate further free radicals (Cadet and Brannock 1998; Graham, 1978)). Among many other potential toxic effects on cells, dopamine oxidation products have been shown to impair mitochondrial functioning (Berman and Hastings 1999). There is currently little direct evidence to support a role for dopamine metabolites in MDMA neurotoxicity. Some dopaminergic drugs alter MDMA neurotoxicity, but it is not clear that this is due to increasing or decreasing dopamine release. Many dopaminergic drugs are now thought to affect MDMA neurotoxicity through nonspecific mechanisms such as altering body temperature (Colado, 1999a; Malberg, 1996) or scavenging free radicals (Sprague and Nichols 1995a; b; Sprague, 1999). However, dopamine release does seem to play a poorly understood role in MDMA neurotoxicity (Nash and Brodkin 1991; Schmidt, 1990; Shankaran, 1999b; Stone, 1988)."

And then you take into account that "LSD affects a large number of the G protein-coupled receptors, including all dopamine receptor subtypes, and all adrenoreceptor subtypes, as well as many others." https://en.wikipedia.org/wiki/Lysergic_acid_diethylamide

You have a lot more dopamine then if you just took MDMA and dopamine can damage your serotonin glands if it gets inside them. Something that happens when your coming down of it.