Here are the things people are most frightened by, and what they actually are.
Psilocybin raises heart rate and blood pressure a little. Anxiety raises it a lot more. What you are feeling is almost certainly the anxiety, and it will settle as the anxiety does. Sit down. Breathe out for longer than you breathe in.
This is one of the most common things people feel at the peak of a strong dose, and it is not information about your body. Nobody has died from psilocybin toxicity, the amount required is enormous and unreachable by eating mushrooms. The feeling is the drug, not a diagnosis.
You have not. Psilocin is cleared from your body in hours and does not cause structural damage. Every person who has had a hard experience has had this exact thought during it, and it goes away with the drug.
Loss of the ordinary sense of being a person in a place is a standard effect at higher doses. It is temporary and it reverses completely. You do not need to solve it. Lie down, and let it happen rather than fighting it, resistance is what makes this part frightening.
Time perception is one of the first things psilocybin disrupts, so a few minutes can feel like hours. That feeling is itself an effect of the drug. It has an end, your body is already clearing it, and the clock is moving normally even though it does not feel that way.
Nausea is normal during the come-up and usually passes at the peak. Sip water. If you vomit after the first hour, most of the dose is already absorbed, so it will not end the experience, but you will probably feel better.
Shivering, cold hands and feet, and yawning are ordinary come-up effects. Put a blanket on. It is not a fever and it is not shock.
Emotion arrives in waves and much larger than usual. Crying is very common and is not a sign anything is wrong. Let it happen; it passes like everything else here.
Nothing has started yet. Your stomach is still converting psilocybin to psilocin. That takes 20 to 60 minutes.
Psilocin is entering your bloodstream and binding 5-HT2A receptors. Effects will keep building for about an hour.
Psilocin in your blood is at its highest. Normal communication between brain networks is loosened. This is the strongest it gets.
Psilocin is clearing. Its half-life is about two to three hours, so the level in your blood is now roughly halving.
The main effects are over. What is left is tiredness, some residual mood change and a nervous system that has had a long day.
If what is happening is not on this page, that does not mean something is wrong. It means this page is short. The things that genuinely warrant a phone call are listed here, and the list is shorter than you think.