25i (25I‑NBOMe) is a synthetic hallucinogenic drug in the NBOMe family that is sometimes misrepresented and sold as LSD or other psychedelics. (Source) It was first synthesized in 2003 by a researcher at the Free University of Berlin as part of scientific work on serotonin receptors, not for human use. (Source)

25i is considered a designer drug because it was created in a laboratory to mimic and intensify the effects of classic hallucinogens like LSD and mescaline. (Source) After its chemistry was published, underground labs began producing it illegally and distributing it worldwide through street dealers and online markets.

Compared with many other illegal drugs, 25i is relatively inexpensive per dose, which can make it especially appealing to teens and young adults. (Source) However, the low price hides an extremely high risk: the active dose is measured in micrograms, so a very small error in dosing can lead to seizures, organ failure, or death.

Like fentanyl, 25i can be active in very small amounts, and there have been reports of toxicity from accidental exposure to powders or liquids. (Source) Because of its high risk of serious harm and lack of accepted medical use, 25I‑NBOMe is classified as a Schedule I controlled substance in the United States. (Source)

Using 25i even once can result in a medical emergency, long‑term psychological problems, or fatal overdose, especially when the person believes they are taking LSD and is unaware of the drug’s true potency. (Source)

In the United States, the Drug Enforcement Administration (DEA) uses a scheduling system (Schedule I–V) to classify controlled substances based on their medical use and potential for abuse and dependence. (Source)

• Schedule V drugs have the lowest potential for abuse and often contain limited quantities of certain narcotics, such as some cough medicines with small amounts of codeine and medications like pregabalin (Lyrica) or diphenoxylate/atropine (Lomotil). (Source)

• Schedule IV drugs have a low but real potential for abuse and dependence. Common examples include benzodiazepines and sedative medications such as diazepam (Valium), lorazepam (Ativan), and zolpidem (Ambien). These medications are only legally available with a prescription from a licensed medical provider. (Source)

• Schedule III drugs have a moderate to low potential for physical and psychological dependence. Examples include anabolic steroids, ketamine, certain testosterone products, and combination products like acetaminophen with codeine. (Source)

• Schedule II drugs have a high potential for abuse and can lead to severe psychological or physical dependence. They include many prescription opioids and stimulants such as fentanyl, oxycodone, methadone, methamphetamine, and mixed amphetamine salts (Adderall). (Source)

• Schedule I drugs are considered the most dangerous controlled substances. They have no currently accepted medical use in the United States and a high potential for abuse and dependence. (Source) Examples include heroin, LSD, MDMA (ecstasy), and synthetic hallucinogens in the NBOMe family, including 25I‑NBOMe. (Source)

Because 25i is a Schedule I drug, manufacturing, distributing, or possessing it is illegal under federal law. (Source) More importantly for individuals and families, Schedule I status reflects the reality that 25i can cause severe toxicity, unpredictable behavior, and death, even in people who have never used drugs before. (Source)

25i belongs to a group of synthetic compounds known as NBOMes (N‑methoxybenzyl derivatives of the 2C family of phenethylamines). (Source) Chemically, 25I‑NBOMe is derived from the psychedelic phenethylamine 2C‑I, with an added N‑(2‑methoxybenzyl) group that greatly increases its potency at serotonin receptors in the brain. (Source)

Because of this modification, 25i is active at extremely low doses—often in the microgram range—making it far more potent than many older hallucinogens. (Source) This narrow margin between a “recreational” dose and a toxic or lethal dose is one of the main reasons 25i is so dangerous.

On the street, 25i is often marketed under names like:

• 25I‑NBOMe
• N‑bomb or N‑bombs
• Smiles
• Synthetic LSD or “legal acid” (even though it is illegal in the U.S.) (Source)

Because it is a synthetic chemical produced in clandestine labs, the purity and exact composition of 25i products can vary widely. (Source) Some samples sold as 25i may contain other NBOMe compounds or completely different substances, further increasing the risk of overdose and unpredictable side effects. (Source)

25i primarily acts on serotonin 5‑HT2A receptors in the brain, the same receptors targeted by classic psychedelics like LSD and psilocybin. (Source) These receptors are especially concentrated in the frontal cortex, a region involved in perception, decision‑making, and mood regulation. (Source)

By powerfully stimulating 5‑HT2A receptors, 25i can cause intense visual and auditory hallucinations, altered sense of time, and profound changes in thought patterns and emotions. (Source) However, because 25i is a full agonist at these receptors and is highly potent, the effects can be much more extreme and less predictable than those of traditional psychedelics. (Source)

Excessive serotonin activity in the brain and body can also contribute to a dangerous condition known as serotonin syndrome, especially when 25i is combined with antidepressants, MDMA, or other serotonergic drugs. (Source) Serotonin syndrome can develop quickly and may include:

• Agitation or restlessness
• Confusion or disorientation
• Rapid heart rate and high blood pressure
• Muscle rigidity, twitching, or spasms
• Heavy sweating and fever
• Seizures

Without prompt medical treatment, severe serotonin syndrome can be fatal. (Source)

People with underlying mental health conditions such as psychosis, bipolar disorder, or severe anxiety may be especially vulnerable to prolonged or worsening symptoms after using 25i, including paranoia, panic, or persistent hallucinations. (Source)

Like LSD, 25i is often distributed on small pieces of blotter paper that are placed under the tongue or against the cheek, allowing the drug to absorb through the lining of the mouth. (Source) Because the active dose is so small, a single blotter square can contain enough 25i to cause severe toxicity.

However, blotter is not the only way 25i is used. It may also appear as:

• Liquid drops placed on blotter, candy, or directly into the mouth
• Powder that is snorted (insufflated)
• Powder or liquid mixed with other substances and smoked
• Powder or solution prepared for injection in rare but extremely high‑risk cases (Source)

Even a few grains of powder—similar in size to grains of table salt—can contain a potentially lethal dose of 25i. (Source) Because the drug is active at such low levels, it is very difficult for users or dealers to measure doses accurately without specialized equipment.

Accidental exposure can also occur when people handle powders or liquids without protective equipment, or when 25i is misrepresented as LSD and taken in doses appropriate for LSD but far too high for NBOMe compounds. (Source)

Any suspected exposure to 25i, especially if followed by confusion, agitation, or unusual physical symptoms, should be treated as a medical emergency.

The effects of 25i can vary widely from person to person and from dose to dose. Onset is often within 15–45 minutes after ingestion, with effects lasting 6–10 hours or longer. (Source)

Common short‑term effects may include:

• Rapid or extreme mood changes
• Intense visual and auditory hallucinations
• Distorted sense of time and reality
• Chills or sweating
• Increased energy or restlessness
• Euphoria or a feeling of being “out of body”
• Muscle spasms or jaw clenching
• Paranoia, anxiety, or panic attacks (Source)

More severe or dangerous effects can include:

• Very high body temperature (hyperthermia)
• Rapid heart rate and elevated blood pressure
• Irregular heartbeat
• Numbness or tingling
• Severe agitation or aggression
• Confusion, delirium, or psychosis
• Seizures
• Loss of consciousness or coma (Source)

Because 25i can cause extreme hallucinations and distorted judgment, people under its influence may engage in highly risky behaviors, such as jumping from heights, running into traffic, or attempting dangerous stunts because they believe they are invincible or can fly. (Source) Fatalities have been reported in otherwise healthy young people after a single use of 25I‑NBOMe. (Source)

If someone shows signs of overdose—such as seizures, chest pain, severe agitation, or very high temperature—call emergency services immediately. Do not wait for the person to “come down.” (Source)

One of the most serious complications associated with 25i and other potent stimulatory or hallucinogenic drugs is rhabdomyolysis. This condition occurs when muscle tissue breaks down rapidly and releases proteins and electrolytes into the bloodstream, which can overwhelm the kidneys and other organs. (Source)

Rhabdomyolysis can be triggered by severe agitation, prolonged muscle activity, seizures, or hyperthermia—all of which can occur during a 25i overdose. (Source) Symptoms may include:

• Dark, cola‑colored or bloody‑appearing urine
• Muscle pain, stiffness, or swelling
• Weakness or difficulty moving
• Decreased urine output
• Joint pain
• Nausea, vomiting, or confusion
• Seizures or sudden changes in consciousness (Source)

Without rapid medical treatment, rhabdomyolysis can lead to acute kidney failure, dangerous heart rhythm problems, and death. (Source) Anyone with suspected 25i use who develops severe muscle pain, dark urine, or signs of overheating should be evaluated in an emergency department as soon as possible.

Other potential complications of 25i use include:

• Stroke or heart attack in susceptible individuals
• Persistent anxiety, depression, or psychosis after the drug wears off
• Self‑harm or accidental injury during intoxication (Source)

Even when a person survives an acute overdose, they may face long‑term physical or psychological consequences that require ongoing care and support.

Because 25i is a relatively new synthetic drug, long‑term research on its addiction potential is limited. However, reports suggest that tolerance to its hallucinogenic effects can develop quickly, sometimes after only a few uses. (Source) This means a person may feel they need to take more of the drug to achieve the same effects, which greatly increases the risk of overdose.

While 25i may not cause the same type of physical dependence seen with opioids or alcohol, people can develop psychological dependence, craving intense experiences or using the drug to escape emotional pain or stress. (Source)

Warning signs that 25i or other hallucinogens may be becoming a problem include:

• Using more often or in higher doses than intended
• Continuing to use despite panic attacks, bad trips, or medical scares
• Spending significant time or money obtaining or recovering from the drug
• Neglecting school, work, or relationships because of use
• Using alone or in risky situations

Teens and young adults are particularly vulnerable to experimenting with 25i and other synthetic drugs marketed as “research chemicals” or “legal highs,” often without understanding the real risks. (Source) Early intervention and open, nonjudgmental conversations can help prevent serious harm.

If you suspect that a friend or family member is using 25i, it is important to approach the situation with calm, compassion, and clear concern for their safety.

Possible signs of 25i or other hallucinogen use can include:

• Sudden, intense mood swings or unusual behavior
• Visual or auditory hallucinations
• Paranoia, panic, or extreme anxiety
• Dilated pupils, rapid heart rate, or sweating
• Unexplained injuries or risky behavior
• Blotter paper, unmarked tablets, powders, or small dropper bottles among their belongings (Source)

When you talk with them:

• Choose a calm, private time when they are not intoxicated.
• Express concern using “I” statements (for example, “I’m worried about you because…”).
• Avoid yelling, shaming, or making threats, which can push them away.
• Listen to their perspective and try to understand what they are going through.
• Emphasize that your goal is their safety and well‑being, not punishment.

If the person is currently high and appears confused, aggressive, or physically unwell, prioritize safety. Call emergency services if there are signs of overdose, self‑harm, or danger to others. (Source)

Once the immediate crisis has passed, encourage them to speak with a medical or addiction professional who understands synthetic drugs and can provide an accurate assessment and treatment recommendations. (Source)

Recovering from 25i use or any substance use disorder is challenging, but no one has to do it alone. At Cardinal Recovery, we provide compassionate, evidence‑based care for people struggling with synthetic drugs, hallucinogens, and co‑occurring mental health conditions.

Our team understands the unique risks associated with 25i and other NBOMe compounds, including medical complications, trauma from frightening experiences, and lingering anxiety or mood symptoms. (Source) We work with each person to create an individualized treatment plan that may include:

• Medically supervised detox or stabilization when needed
• Comprehensive medical and psychiatric evaluation
• Individual and group therapy focused on substance use and mental health
• Education about synthetic drugs and relapse prevention
• Family support and communication strategies
• Aftercare planning and connection to ongoing support

From the first phone call, our admissions specialists focus on making the process as straightforward and respectful as possible. We gather essential information about substance use history, prior treatment, medical conditions, and any recent overdoses or hospitalizations so we can recommend the safest level of care. (Source)

We also verify insurance benefits quickly so that financial questions do not become a barrier to getting help. During the transition into treatment, a dedicated team member stays in contact to answer questions, provide reassurance, and help reduce anxiety about the next steps.

Once you or your loved one arrives at the treatment center, our clinical team completes a more detailed assessment and collaborates with you to design a personalized plan. The goal is not only to stop substance use, but also to build the skills, support, and confidence needed for long‑term recovery.

If you are ready to explore treatment options for yourself or someone you care about, reach out to Cardinal Recovery today. A single phone call can be the first step toward safety, healing, and a healthier future.