Originally published April 23, 2024. Revised.
There’s an observation that anyone who spends time around ayahuasca will recognize, and that the research literature has not done much with.
People arrive in ceremony carrying something. Under the medicine, whatever they came in with tends to get louder. Sinuses swell. A fever comes up within the hour. Old aches announce themselves. There’s vomiting and often diarrhea, tremors, sweating, streaming eyes and nose. And then, frequently, in the days afterward, people report feeling better than they have in a long time.
Western medicine has no comfortable place to put that sequence, because it reads symptoms as the disease. A treatment that reliably intensifies symptoms and is then followed by improvement doesn’t fit the frame. So the sequence gets handled two ways, both unsatisfying. Either the medicine is described as magical and beyond explanation, or the improvement is treated as anecdote and set aside.
I want to take the sequence seriously and think about what could account for it.
Ayahuasca is often described as an intensely parasympathetic medicine, and the subjective case for that is strong. The heaviness arrives, the breath slows, the pull to lie down is close to irresistible, and anyone with a background in yoga nidra or deep meditation recognizes the state immediately. Amazonian traditions consistently describe the medicine in receptive, yin, mother terms, and that language is pointing at something real.
The instrumented data complicates the label. In controlled studies, ayahuasca produces moderate increases in blood pressure and heart rate, elevated cortisol, prolactin and growth hormone, raised body temperature, and pupillary dilation. Dos Santos and colleagues, comparing ayahuasca against d-amphetamine and placebo in a double-blind crossover, concluded it displays moderate sympathomimetic effects.
Pupil dilation is the detail that settles it for me. Genuine vagotonia constricts pupils. Ayahuasca dilates them. Whatever is producing the heaviness, it isn’t parasympathetic dominance.
What’s happening looks like both systems firing at once. The purge is vagally mediated and the harmala alkaloids are directly emetic, so there is real parasympathetic activity in the gut while cortisol and heart rate climb. Mixed autonomic activation is a stranger and more interesting phenomenon than simple vagotonia, and it may be closer to why the experience feels the way it does: the body pinned between two states rather than settled into one.
This matters for any explanation built on top of it. A bridge resting on the claim that ayahuasca is parasympathetic has nothing under it.
The assumption that symptoms are the illness is a choice, and often a poor one.
Fever is not the disease, it is an evolved host response that serves a practical healing purpose. Sickness behavior, the lethargy and social withdrawal and loss of appetite, is a coordinated adaptive program rather than a byproduct. Inflammation is the machinery of repair, running visibly. Cough clears the airway. In each case the thing we medicate is the thing doing the work.
That has real clinical consequences. Suppressing a fever can extend the course of an illness. Congestion returns when a decongestant wears off precisely because the decongestant works by adrenergic vasoconstriction, squeezing the vessels shut and doing nothing about why the tissue was inflamed. Decongestants are a genuine case of a drug that trades repair for relief. They are also one of a fairly small number, and the pattern doesn’t generalize across conventional medicine the way it sometimes gets stretched to. Antibiotics, insulin, thyroid hormone and anticoagulants work nothing like this.
So the reframe is available without leaving mainstream physiology. If symptoms are frequently the repair process rather than the damage, then a substance that intensifies symptoms may be intensifying repair, and feeling worse in the middle of it is not evidence that something has gone wrong.
Applied to ceremony, that gives a plausible reading of the sequence. Whatever process was already underway gets amplified under the medicine, runs harder and faster than it would have on its own, and completes. The improvement afterward isn’t the ayahuasca curing anything. It’s the body finishing something it had been carrying half-done.
A lot of people in this world reach for German New Medicine to explain exactly this, and since many readers here already work with that framework, I want to lay out what it would say and be straight about its standing.
GNM, developed by Ryke Geerd Hamer, proposes that disease begins with an unexpected biological conflict shock registering simultaneously in psyche, brain and organ. During the conflict-active phase the person sits in sympathetic tone, adapting and largely asymptomatic, sometimes with high energy, cold extremities, poor sleep. When the conflict resolves, the body swings into a parasympathetic healing phase, and that is when symptoms appear. On this account symptoms mean the conflict has been resolved, and their intensity tracks the severity and duration of what preceded them.
If that framework were accurate, ayahuasca would map onto it neatly. The medicine would be a device for reaching and resolving conflicts, and the symptoms that erupt in ceremony would be healing-phase phenomena arriving all at once. That is a genuinely elegant fit, and I understand why people who work with both find the correspondence compelling.
I’m not in a position to tell anyone that framework is false, and I’m not attempting to here. What I’d note is that GNM sits outside mainstream medicine, its central claims about conflict shocks and their correlates have not been independently replicated, and Hamer’s own history with medical authorities is easy enough to look into for anyone who wants the full picture. Readers can weigh that for themselves.
None of that means the underlying observation is worthless. Psychoneuroimmunology has established in ordinary terms that stress and emotional states shape immune function and inflammation, and the intuition that a shock can precede a disease is not exotic.
There is one point I’d ask people to hold carefully, and it’s the practical one rather than the theoretical one. If symptoms are read as proof that healing is already underway, that reading can become a reason not to seek care. Nothing here is a reason to decline treatment for a diagnosed condition. If you’re working with something serious, work with it alongside people qualified to treat it.
Stripped back, the defensible version is small, and I’d rather have a small true thing.
Ayahuasca produces mixed autonomic activation rather than parasympathetic dominance. Symptoms in general are frequently repair rather than damage, and that’s mainstream physiology, not a fringe position. A substance that intensifies symptoms may therefore be intensifying repair. That is enough to account for the sequence people describe, and it gets there without needing anything beyond ordinary physiology.
Whether GNM adds anything beyond that, I don’t know. It’s an interpretive frame that a lot of people find makes sense of their experience, and parts of it map onto things I’ve watched happen.
So we have a real and repeatable observation, an ordinary physiological reading that covers a good deal of it, and a more elaborate framework that covers it more neatly. I’d rather sit with both than pick a side prematurely. The ceremonies keep happening either way, and the people in them keep getting better in ways nobody has adequately explained.
References
Dos Santos, R. G., Valle, M., Bouso, J. C., et al. (2011). Autonomic, neuroendocrine, and immunological effects of ayahuasca: a comparative study with d-amphetamine. Journal of Clinical Psychopharmacology, 31(6), 717-726.
Riba, J., Valle, M., Urbano, G., et al. (2003). Human pharmacology of ayahuasca: subjective and cardiovascular effects, monoamine metabolite excretion, and pharmacokinetics. Journal of Pharmacology and Experimental Therapeutics, 306(1), 73-83.