Short answer: You may notice some effects between 10 and 40 minutes, and you will really know that you are tripping after 2 hours. The trip will “peak” around 3-4 hours after ingestion, and you’ll still very much be tripping after 8 hours, with effects waning 7-9 hours after consuming LSD.
A research study published in 1955, while acid was still legal, found that changes in perception began to be noticed between 10 and 40 minutes after ingestion of a dose of ~70 micrograms.
They found the maximum effects of acid were mostly felt at 3 hours after ingestion (4.5 hours after ingestion in one subject).
Graph from a 1962 paper using 100 micrograms of LSD.
Read our page how to take acid/LSD.
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