Short answer: Chlordiazepoxide (Librium) was the first benzodiazepine, introduced in 1960. It is a long-acting Schedule IV prescription medicine used for anxiety and, most often today, to manage alcohol withdrawal. Like all benzodiazepines it can cause dependence, and it is dangerous with opioids or alcohol.
Key takeaways
- What it is: Chlordiazepoxide is a long-acting benzodiazepine and a Schedule IV controlled substance in the US.
- Main uses: Anxiety; alcohol withdrawal.
- Timing: effects start in 30 minutes to 2 hours and last long; active metabolites last days.
- Most dangerous mix: Opioids (oxycodone, hydrocodone, fentanyl, heroin), which can cause profound sedation, slowed breathing, coma, death.
- Naloxone: it does not reverse this drug, but give it whenever opioids could be involved.
- Dependence risk: High.
- Legal route: only with a prescription from a DEA-registered clinician, filled by a licensed pharmacy.
What is chlordiazepoxide?
Chlordiazepoxide treats anxiety and the agitation, tremor, and seizure risk of acute alcohol withdrawal. Its long-lasting metabolites give a smooth, self-tapering effect, which is why it remains a standard choice for alcohol withdrawal.
Combined with clidinium in Librax it is used for irritable bowel syndrome and peptic ulcer symptoms.
Quick facts
| Fact | Chlordiazepoxide |
|---|---|
| Generic name | Chlordiazepoxide hydrochloride |
| Brand names | Librium; with clidinium: Librax; with amitriptyline: Limbitrol (discontinued) |
| Drug class | Long-acting benzodiazepine |
| US legal status | Schedule IV, prescription only |
| Approved uses | Anxiety disorders; acute alcohol withdrawal; anxiety before surgery |
| Forms | Capsules (5, 10, 25 mg) |
| Onset | 30 minutes to 2 hours |
| Half-life | 5 to 30 hours, with active metabolites such as desmethyldiazepam lasting days |
| Reversal agent | Flumazenil (hospital use only) |
How long does chlordiazepoxide last?
- Starts working: 30 minutes to 2 hours
- Effects last: Long; active metabolites last days
- Half-life: 5 to 30 hours, with active metabolites such as desmethyldiazepam lasting days
Its metabolites can be detected in urine for a week or more after regular use.
Timing varies with the dose, the form, how it is taken, liver and kidney function, age, and other drugs taken at the same time.
What are the biggest risks of chlordiazepoxide?
The FDA requires boxed warnings, its strongest, on chlordiazepoxide products, including:
- Use with opioids can cause profound sedation, slowed breathing, coma, and death.
- Abuse, misuse, and addiction, which can lead to overdose and death, especially with alcohol, opioids, or other drugs.
- Physical dependence: stopping suddenly or reducing the dose quickly can cause life-threatening withdrawal reactions, including seizures.
Common side effects include drowsiness, unsteadiness, and confusion, especially in older adults.
Build-up: because its metabolites last days, sedation can increase over the first week and linger after stopping, particularly in older adults and people with liver disease.
What should you never mix with chlordiazepoxide?
| Combined with | What happens | Label guidance |
|---|---|---|
| Opioids (oxycodone, hydrocodone, fentanyl, heroin) | Profound sedation, slowed breathing, coma, death | Boxed warning; avoid unless no alternative |
| Alcohol | Deeper sedation, blackouts, slowed breathing | Avoid |
| Other sedatives (sleep medicines, gabapentinoids, muscle relaxants, antihistamines) | Additive drowsiness and impaired coordination | Use caution |
| Strong CYP3A4 inhibitors (ketoconazole, ritonavir) | Higher levels and more sedation | Use caution |
| Clozapine and other antipsychotics | Additive sedation; rare breathing problems | Use caution |
Check any combination with the DoseUses combination checker or ask a pharmacist.
What are the signs of a chlordiazepoxide overdose, and what should you do?
Chlordiazepoxide overdose causes deep drowsiness, confusion, poor coordination, slowed reflexes, and coma. With opioids or alcohol, breathing can stop.
If someone may have overdosed
- Call 911 if the person is unresponsive, hard to wake, or breathing slowly.
- For advice when the person is awake and stable, call Poison Help at 1-800-222-1222 (US, free, 24 hours).
- If opioids could be involved, including pills not from a pharmacy, give naloxone if you have it. Naloxone does not reverse chlordiazepoxide, but it will not harm the person.
- Stay with the person and place them on their side if they are drowsy or vomiting.
What is chlordiazepoxide withdrawal like, and how long does it last?
People who take chlordiazepoxide regularly, even as prescribed, can become physically dependent within weeks. Its very long-lasting metabolites mean withdrawal often starts several days after the last dose.
- Days 3 to 7Symptoms beginRebound anxiety, insomnia, restlessness, sweating, and tremor.
- Weeks 1 to 4Acute withdrawalPanic, irritability, muscle pain, nausea, sensitivity to light and sound, and in severe cases seizures or delirium.
- MonthsProtracted symptoms in some peopleA minority have lingering anxiety, poor sleep, low mood, or tingling that can last weeks to more than 12 months.
See the withdrawal timelines and the full chlordiazepoxide withdrawal guide.
Is chlordiazepoxide legal?
In the United States, chlordiazepoxide is a Schedule IV controlled substance. The only legal way to get it is with a prescription from a clinician registered with the Drug Enforcement Administration (DEA), filled by a licensed pharmacy. Depending on state law, that can be a physician, nurse practitioner, or physician assistant.
- Refills: a Schedule IV prescription can be refilled up to five times within six months of the date it was written. After that, a new prescription is needed.
- Telehealth: federal flexibilities let DEA-registered clinicians prescribe Schedule II to V medicines after a telemedicine visit, without a prior in-person exam, through December 31, 2026. A permanent DEA rule was under final review in late 2026. State rules can be stricter.
- Monitoring: prescribers and pharmacists in most states check a prescription drug monitoring program, a database of controlled-substance prescriptions, before prescribing or dispensing.
Outside the United States
| Country | Status |
|---|---|
| United Kingdom | Class C; prescription only |
| Canada | Schedule IV of the Controlled Drugs and Substances Act |
| Australia | Schedule 4 prescription medicine |
| International | Schedule IV of the 1971 Convention on Psychotropic Substances |
Frequently asked questions about chlordiazepoxide
Is Librium used for alcohol withdrawal?
Yes. It is one of the most commonly used medicines to prevent seizures and severe symptoms during alcohol withdrawal.
Is Librium stronger than Xanax?
Milligram for milligram it is weaker, but it lasts much longer. About 25 mg of chlordiazepoxide is roughly equivalent to 0.5 mg of alprazolam.
How long does chlordiazepoxide stay in your system?
Its metabolites can be detected in urine for a week or more after regular use.
Can you drink alcohol on Librium?
No. Alcohol adds to sedation and can stop breathing.
Is chlordiazepoxide addictive?
It can cause dependence and addiction, like other benzodiazepines, especially with long-term use.
Sources
- Librium (chlordiazepoxide) prescription information, DailyMed, US National Library of Medicine.
- FDA warns about serious risks and death when combining opioid pain or cough medicines with benzodiazepines, US Food and Drug Administration, 2016.
- FDA requiring Boxed Warning updated to improve safe use of benzodiazepine drug class, US Food and Drug Administration, 2020.
- Joint Clinical Practice Guideline on Benzodiazepine Tapering, American Society of Addiction Medicine, 2025.
- Controlled Substance Schedules, DEA Diversion Control Division.
- 21 CFR 1306.22, Refilling of prescriptions (Schedules III and IV), Electronic Code of Federal Regulations.
- Prescribing controlled substances via telehealth, US Department of Health and Human Services.
- BeSafeRx: Your Source for Online Pharmacy Information, US Food and Drug Administration.
This guide summarizes the sourced DoseUses Chlordiazepoxide profile, written from FDA labels, DEA rules, and federal health agencies. It is educational and is not medical advice. Last updated October 5, 2026.
