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Nembutal Side Effects

Generic name: pentobarbital

Medically reviewed by Last updated on Mar 3, 2022.

Note: This document contains side effect information about pentobarbital. Some of the dosage forms listed on this page may not apply to the brand name Nembutal.

For the Consumer

Applies to pentobarbital: parenteral solution for injection


Special Alerts:

A standardized concentration for this drug has been established through Standardize 4 Safety (S4S), a national patient safety initiative to reduce medication errors, especially during transitions of care. The drug is included in a standard concentration list which may apply to an IV or oral compounded liquid formulation. For additional information, see the ASHP website [Web].

Side effects include:

Residual sedation, drowsiness, lethargy, vertigo, nausea, vomiting, headache.

For Healthcare Professionals

Applies to pentobarbital: compounding powder, injectable solution, oral capsule, oral elixir, rectal suppository

Nervous system

Common (1% to 10%): Somnolence

Uncommon (0.1% to 1%): Ataxia, central nervous system (CNS) depression, dizziness, hyperkinesia, syncope

Frequency not reported: Headache[Ref]


Uncommon (0.1% to 1%): Abnormal thinking, agitation, anxiety, confusion, dizziness, hallucination, nervousness, nightmares, psychiatric disturbance[Ref]


Uncommon (0.1% to 1%): Constipation, nausea, vomiting[Ref]


Uncommon (0.1% to 1%): Apnea, hypoventilation[Ref]


Uncommon (0.1% to 1%): Bradycardia, hypotension[Ref]


Frequency not reported: Angioedema, hypersensitivity reactions[Ref]


Frequency not reported: Exfoliative dermatitis, skin rashes[Ref]


Megaloblastic anemia occurred with chronic phenobarbital use.[Ref]

Frequency not reported: Megaloblastic anemia[Ref]


Frequency not reported: Liver damage[Ref]


Frequency not reported: Fever[Ref]


Frequency not reported: Injection site reactions[Ref]

More about Nembutal (pentobarbital)

Patient resources

Other brands

Nembutal Sodium

Professional resources

Related treatment guides


1. "Product Information. Pentobarbital (pentobarbital)." Wyeth-Ayerst Laboratories (2001):

2. "Product Information. Nembutal Sodium (pentobarbital)." Abbott Pharmaceutical (2001):

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.