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How Long Does Acid/LSD Stay in Your System?

People have used mind-altering substances for thousands of years. However, modern drugs of abuse are more potent, addictive, and often with more predictive action.

Regretfully, the use of illicit drugs is rising in many parts of the world. These drugs are illegal as they have well-known and proven harmful effects on health.

LSD is a short form for lysergic acid diethylamide, or simply acid. It’s a potent hallucinogenic agent, meaning that it alters perception completely. A person starts feeling that does not exist physically exist1.

How long does acid last?

Most LSD sold in the illicit market is of quite a high purity. It has a predictable absorption by the body, known bioavailability, and duration of action. Quite like any other drug, the body would start absorbing it after about 20 minutes of oral intake.
However, it may take much longer to achieve its peak action, as complete absorption by the intestines may take up to 90 minutes. There are considerable individual differences. Additionally, the absorption rate also depends on the food intake.
Most habitual users call the mind-altering effect of acid “a trip.” Generally, the trip would last anywhere between 6 to 15 hours. But, again, there are massive individual differences. Additionally, lots depend on the experience of users. Generally, on average, trips last for about 12 hours2.
However, some drug effects continue to influence the mind and body for 24 hours. Additionally, it is worth understanding that drugs remain in traces in the body for much longer. Some of the sensitive tests can detect it for 90 days after using the drug. Generally, acid is detectable in hair follicles for several weeks.

How does acid work? And why does its trip last so long?

Acid is classified as a potent psychoactive agent with long-lasting action in the medical world. Its primary effect is hallucinogenic.
Quite like many other drugs of abuse, the pharmaceutical industry researchers first created acid. Researchers at the Swiss company Sandoz first isolated it from the fungus for rye and grain. So, yes, it has natural origins. But it has a simple chemical structure, and thus its synthetic production does not pose much challenge3.

In the following years, researchers started to study its mechanism of action. Science is particularly interested in mind-altering substances as it wants to create medications for various neurological and psychiatric conditions.

Studies show that acid is quite similar to one of the best-known neurotransmitters- serotonin. Serotonin plays a central role in mood regulation. Its disbalance is associated with conditions like depression.

Since acid acts like serotonin in the brain, it can bind to serotonin receptors and thus cause a high or a trip. However, unlike natural serotonin that acts on receptors for a few seconds before being neutralized, it continues to bind with receptors for several hours. Thus, it can continue to produce these effects for 6-15 hours.

The human body has many neurotransmitters that control mood and perception, and among them, serotonin is most vital. However, the body has a robust mechanism of controlling its action. An enzyme system neutralizes these neurotransmitters in milli-seconds or immediately once they have served their purpose.

But the body has no way to overcome synthetic chemicals imitating these natural compounds. Moreover, acid has a so-called high affinity for serotonin receptors. Thus, it remains stuck on these receptors for several hours before the body’s defensive mechanism can knock it down.

How is the acid used, and is it safe?

Of course, acid is not going to kill a person instantly. However, it is an illicit drug as it does not have any medical use. Moreover, it is addictive, and its prolonged use causes many ill health effects. Additionally, its use may also alter behavior.

Nevertheless, it is good to know that acid is among the safer oral drugs available as pills, caps, or even sugar cubes. Thus, people take it orally. It is among the safer illicit drugs that rarely cause severe toxicity or death. However, sometimes, severe side effects may occur due to overdose.

Additionally, one is also likely to have a so-called “bad trip.” Again, it is something difficult to predict, but some may have frightening hallucinations.
Furthermore, it is worth knowing that those regularly using acids may develop resistance. However, this resistance is short-lived, and a person may again become sensitive to it on discontinuation for a few weeks.

How much acid is safe?

Acid is not a medication; thus, there cannot be any official recommendations regarding its dosage. However, users’ experience shows that a 1-3 microgram per kg body weight dose is enough for a moderate trip. Thus, most illicitly sold dosages would have 30 to 100 micrograms of the drug.
But, there is no way to know the exact amount of LSD in a tablet or capsule, as it is not a legal drug and is not tested by regulatory agencies.
To conclude, LSD or acid is a potent hallucinogenic drug used for a prolonged trip that may be pleasant or unpleasant. Furthermore, it is a relatively safe drug. Finally, it is worth understanding that it is illegal to possess or use acid and is a controlled substance.


  1. Wacker D, Wang S, McCorvy JD, et al. Crystal Structure of an LSD-Bound Human Serotonin Receptor. Cell. 2017;168(3):377-389.e12. doi:10.1016/j.cell.2016.12.033
  2. Abuse NI on D. How Do Hallucinogens (LSD, Psilocybin, Peyote, DMT, and Ayahuasca) Affect the Brain and Body? National Institute on Drug Abuse. Published –. Accessed February 26, 2022.
  3. The accidental discovery of LSD (video). American Chemical Society. Accessed February 26, 2022.