Hallucinogen persisting perception disorder (HPPD) is a condition that causes an individual to experience sensory disturbances that can mimic those brought on by prior drug use. HPPD occurs among users of hallucinogenic recreational drugs, most commonly lysergic acid diethylamide (LSD).

When someone is referring to an “acid flashback,” they may be referring to hallucinogen persisting perception disorder, but this is often a different phenomenon. Generally, HPPD is a more permanent or chronic state whereas a flashback is a single occurrence. An individual can only be diagnosed with HPPD if they are no longer taking hallucinogenic drugs.

Hallucinogens are drugs that alter a user’s perception of the world around them. According to the National Institute on Drug Abuse (NIDA), people have been using hallucinogens for centuries. These drugs have been popular in the United States for years. The 1960s saw rampant use of drugs like LSD, and according to Medical Daily, use appears to be on the rise once again. The 2015 National Survey on Drug Use and Health showed that more than 15 percent of people ages 12 and older had used a hallucinogen at least once in their lifetime. Nearly 10 percent of those people had used LSD in particular.

Prevalence of Hallucinogen Persisting Perception Disorder


Reports of hallucinogen persisting perception disorder are extremely uncommon, even among the population of hallucinogenic drug users. It can only occur in people who have taken a hallucinogenic substance, and per Patient, it appears less common among first-time or one-time users of hallucinogens. However, it is possible for someone who used the drug just once to experience HPPD. Risk factors outside of the consumption of hallucinogenic are difficult to pin down due to the rarity of the condition.
The prevalence of hallucinogen persisting perception disorder is unclear, partially due to its rarity. An article published in Drug and Alcohol Dependence details a survey that dealt with more than 2,500 hallucinogen users. While more than 60 percent of these users reported having drug-free visual experiences similar to those brought on by hallucinogens, just 4 percent of the participants found their symptoms severe enough to seek medical attention. This study suggested that long-term visual changes in users could be more common than expected due to a lack of reporting.

The length of time that HPPD affects an individual can vary. Some people experience symptoms for months while others can see the effects last years. A study published in Therapeutic Advances in Psychopharmacology looked at a woman who had developed HPPD when she was 18 and was still suffering from symptoms at 33 years old. Another study, this one published in the British Journal of Medical Practitioners, analyzed a man who had suffered from HPPD for 25 years. These instances show that HPPD can be a long-term condition, and due to its substantial effects, it can have great impact on an individual’s quality of life.

Prevention, Management, and Treatment


The best method for preventing hallucinogen persisting perception disorder is to avoid the consumption of hallucinogenic substances altogether. One cannot suffer from this condition without a history of using hallucinogens. However, taking a drug of this nature in no way guarantees the onset of HPPD, and many users never experience any symptoms of the disorder.

For those who HPPD does affect, there are management and treatment options. There is no cure for this condition, but a multitude of pharmacological approaches have seen success in managing it. Benzodiazepines, anticonvulsants, clonidine, and neuroleptics have all been used to treat individuals suffering from HPPD successfully. In the case of the aforementioned 33-year-old woman suffering from HPPD, her symptoms were quelled with the use of lamotrigine, an anticonvulsant. In the case of the man who had suffered from HPPD for 25 years, his condition was helped by the use of clonazepam, a benzodiazepine sedative.

There are some techniques that do not involve medication that can help an individual deal with symptoms related to hallucinogen persisting perception disorder. Due to its similar effects to benzodiazepines, valerian root has been known to alleviate symptoms of the disorder. As bright light can be a trigger for HPPD in some people, sunglasses can decrease the likelihood of experiencing episodes of the disorder.

Some people with hallucinogen persisting perception disorder see their symptoms dissipate within a matter of months on their own. Those who seek medical treatment often see their symptoms subdued and eventually eliminated altogether by medication. However, for some, the condition is long-lasting and appears to be irreversible. It is recommended that those experiencing HPPD seek medical attention from a specialist. Medications can be key to managing the disorder, and they should be used in conjunction with comprehensive therapy.