Acid is a hallucinogenic drug. Albert Hoffman, a chemist in Switzerland, first developed it in 1938.

Another name for acid is lysergic acid diethylamide (LSD). In the 1950s, doctors used it in psychotherapy and to enhance the effects of antipsychotics. In the late 1960s, people started to use LSD as a recreational drug.

People also refer to LSD by its street names: blotter, dots, and yellow sunshine. It is an illegal drug of abuse and one of the most powerful mood-changing substances.

In this article, we describe how long LSD stays in the body and how long tests can detect it after a person takes a dose. We also discuss the effects and risks.

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Researchers can use blood and urine tests to detect acid in the system.

When a person takes LSD orally, the gastrointestinal system absorbs it and channels it into the bloodstream. Once the drug is in the bloodstream, it travels to the brain and other organs, such as the liver. The liver breaks down LSD into different chemicals.

Researchers experience many challenges when detecting LSD in human tissue samples. People only ingest small amounts, so detection methods need to be very sensitive.

LSD is also unstable, and the liver breaks it down rapidly. The time that LSD is detectable in the tissues is restrictive, so doctors need to analyze the samples quickly.

Some researchers have attempted to develop detection methods for the byproducts of LSD. However, the amounts of these substances that remain in the tissues are still very low.


When a person takes LSD orally, the liver transforms it into inactive compounds. In 24 hours, a person excretes only about 1% of LSD unchanged in the urine.

Researchers can use various methods to detect LSD in urine samples, but these techniques are not readily available. Most routine urine drug tests will not detect LSD.

Two techniques that researchers can use to detect LSD in urine are liquid-liquid extraction and ultra-high-performance liquid chromatography-tandem mass spectroscopy (UHPLC-MS/MS).

Studies have demonstrated that some inactive byproducts of LSD are present in urine at concentrations 16–43 times higher than LSD. Researchers are uncertain how these findings can help detect LSD use, however.


Doctors can also use liquid-liquid extraction and UHPLC-MS/MS to detect LSD in blood samples.

In a recent study, researchers took 13 blood samples within 24 hours of administering LSD. They kept the samples at below freezing temperatures and analyzed them within 12 months.

The researchers could detect LSD in samples taken up to 16 hours after administration in all the participants who had received 200 micrograms (mcg) of LSD.

In those who had received 100 mcg of LSD, the researchers could detect the drug in samples taken up to 8 hours after administration.

The amount of detectable LSD in the samples decreased over time in both groups. In the group who had received 100 mcg of LSD, the researchers could only detect the drug in 9 out of 24 samples after 16 hours.

These detection methods are highly sensitive and specialized, and they may not be readily available to doctors.


Hair samples are useful for detecting drugs that a person used a long time ago. They are also useful when blood or urine samples are unavailable.

Depending on the drug, researchers can estimate the time and duration of ingestion by analyzing the hair’s growth rate and the position of the drug’s evidence on the hair shaft.

Research from 2015 looked at three documented cases of LSD traces in human hair samples. The amount of LSD in the samples was between 1 and 17 picograms per milligram.

However, the researchers performed these tests on hair treated with LSD, rather than from hair samples of people who had taken the drug.

One major challenge that researchers have when using hair samples to detect LSD is that the drug is active at very low doses. If a person had to take a higher dose to feel any effect, the drug might be easier to detect.

There is very spare data on LSD in hair samples. Researchers are even unsure whether the drug is stable and detectable in these samples.

A negative result from a hair sample does not mean that the person has not taken LSD. Pubic hair samples, however, may have been contaminated with LSD from urine.

Other tissues

Researchers have analyzed tissue samples in mice that had received intravenous injections of LSD. They found LSD in the blood, brain, liver, kidneys, adrenal glands, thymus, lungs, and salivary glands.

Autopsy reports may also be able to detect LSD in humans. The journal Forensic Science International published findings from three autopsy reports that included LSD.

According to the researchers, this was the first analysis of LSD and its inactive compounds in human brain tissue. They found evidence of LSD in brain tissue samples, but it was not the cause of death in any of the cases.

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Current tests are unable to detect LSD in the urine after 72 hours.

Many things can influence how long LSD is detectable, including a person’s overall health, their age, and how much of the drug they have taken.

One of the most important factors is the timing of the sample. LSD leaves the blood after about 24 hours.

Current tests are not able to detect LSD or its byproducts in urine samples after 72 hours.

In addition, other drugs that are similar in structure may interfere with the detection of LSD, depending on the test — some are more accurate than others.

For example, some tests have high false-positive rates, which means that they detect LSD when it is not present.

After a dose of 1–3 mcg per kilogram of body weight, most people will experience a moderate effect of LSD.

People can expect to start feeling the effects 30–60 minutes after taking the drug. The effects may last 8–12 hours or more, depending on the dose.

While on LSD, people may experience altered awareness of surrounding objects, conditions, thoughts, and feelings.

One person may have a completely different experience from someone else after taking the same amount of the drug.

A person on LSD may have a “good trip,” which can be filled with bright hallucinations and a feeling of euphoria. Or, they may have a bad trip, involving hallucinations that cause anxiety, panic, fear, depression, despair, disappointment, or a combination.

Some people report flashbacks when using LSD. Stress, fatigue, and taking other drugs at the same time can make these flashbacks more likely. Also, a person who has used LSD in the past may have a flashback to a trip.

Other effects of LSD can include:

  • increased heart rate
  • increased blood pressure
  • increased breathing rate
  • rise or decrease in body temperature
  • sleeplessness
  • loss of appetite
  • shaking
  • sweating

In the 2016 National Survey on Drug Use and Health, researchers estimated that 1.4 million people aged 12 years or older were currently using hallucinogens, including LSD, in the United States.

In 2015 and 2016, the most commonly used hallucinogens were LSD and ecstasy. LSD is usually taken orally as a film (windowpane), blotter paper (micro dots), on sugar cubes, or as a tablet or capsule.

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It is inadvisable to use LSD when pregnant.

LSD usually does not cause addiction.

Some people experience prolonged psychiatric reactions, such as psychosis, though this is rare. LSD and other hallucinogens have low toxicity to organs, including the brain, even at high doses.

There have been no studies of flashbacks in clinical settings, so doctors are unsure whether they are due to LSD alone.

The most significant risk of taking LSD is the dangerous behavior that can result from the effects of the drug. When a person’s perception of the world is altered, they may not pay as much attention to their safety or the safety of others.

Certain other risks can make LSD use inadvisable, including:

People do not typically take LSD daily because of its intense psychological effects. Someone who has been using LSD on a regular basis will quickly develop a tolerance and require higher doses to experience any effects.

A few days after LSD use, a person’s emotional, mental, and physical states usually return to normal. People do not usually get cravings for LSD after stopping, so there are no withdrawal symptoms.

LSD is a powerful, mood-altering chemical and street drug. People usually do not use LSD every day because of its strong psychological effects.

Using certain tests, doctors can detect LSD and its byproducts in urine samples up to 72 hours after a person has taken the drug.

Within 24 hours of taking LSD, some tests can detect it in blood samples. Hair samples are not yet as reliable as urine or blood samples.