Diazepam (Adverse Reactions)

Diazepam is a drug of the benzodiazepine family with anxiolytic, myorelaxant, anticonvulsant and sedative properties. People with reduced CYP2C19 activity may be exposed to a higher dose of the drug.

Diazepam is a derivative of benzodiazepines with anxiolytic, muscle relaxant, anticonvulsant and sedative properties. It facilitates the binding of the neurotransmitter GABA to its neuronal receptor and increases its activity by relaxing the activity of the central nervous system. Acts on the limbic system, thalamus and hypothalamus. It does not produce blocking action of the peripheral autonomic nervous system or extrapyramidal side effects.


Diazepam is contraindicated in individuals with hypersensitivity to benzodiazepines or dependence on other substances, including alcohol (except treatment of acute withdrawal reactions). It is also contraindicated in patients with myasthenia gravis, sleep apnea syndrome, severe respiratory failure, severe hepatic insufficiency, angle-closure glaucoma (rectal, oral administration only), severe chronic hypercapnia (oral administration only).


Precautions should be taken when diazepam is administered in the elderly, in patients with renal insufficiency, mild or moderate hepatic insufficiency. Caution if it is prescribed to children. Care must be taken when prescribing diazepam in patients with chronic respiratory insufficiency, porphyria, epilepsy, or with alcohol/drug dependence or a history of dependence.

In patients with lesions in the CNS and who present epileptic seizures, exercise extreme caution as it may decrease cerebral circulation and blood oxygenation, and may cause irreversible brain damage. Risk of anterograde amnesia, psychiatric and paradoxical reactions.

After a continued use of diazepam there is a risk of tolerance and dependence (physical and mental). Abrupt interruption after continued use causes withdrawal syndrome.

Do not use in anxiety associated with depression or as a primary treatment for psychotic illness.

Taking intravenous diazepam causes risk of apnea and/or cardiac arrest in the elderly, in severely debilitated patients or with limited cardiac or pulmonary reserve.


Drowsiness, affective dullness, reduced alertness, confusion, fatigue, headache, dizziness, muscle weakness, ataxia or diplopia, amnesia, depression, psychiatric and paradoxical reactions; respiratory depression


The depressant effect of diazepam on the central nervous system (CNS) is enhanced with: neuroleptics, hypnotics, anxiolytics/sedatives, antidepressants, narcotic analgesics, antiepileptics, anesthetics, sedative antihistamines.

Sedative effect of diazepam is increased with: alcohol, cisapride, cimetidine, propofol, ethanol.

The action of diazepam is increased by: cytochrome P450 inhibitors, azole antifungals, isoniazid.

There is a CNS and respiratory depressant additive effect with: barbiturates and centrally acting muscle relaxants.

The toxicity of diazepam is increased by: ethinylestradiol and mestranol, fluoxetine, omeprazole, ketoconazole, fluvoxamine, valproic acid.

The effect of diazepam is diminished by: phenobarbital, carbamazepine, phenytoin, rifampicin.

Diazepam increases the action of digoxin and

alters the action of phenytoin.


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  • Tepazepan®

Genes analyzed



Dean L. Diazepam Therapy and CYP2C19 Genotype. 2018 Dec 10 [updated 2020 Oct 15]. In: Pratt VM, Scott SA, Pirmohamed M, Esquivel B, Kattman BL, Malheiro AJ, editors. Medical Genetics Summaries [Internet]. Bethesda (MD): National Center for Biotechnology Information (US); 2012-.

Fukasawa T, Suzuki A, Otani K.Effects of genetic polymorphism of cytochrome P450 enzymes on the pharmacokinetics of benzodiazepines. J Clin Pharm Ther. 2007 Aug;32(4):333-41.

Zubiaur P, Figueiredo-Tor L, Villapalos-García G, et al.Association between CYP2C19 and CYP2B6 phenotypes and the pharmacokinetics and safety of diazepam. Biomed Pharmacother. 2022 Nov;155:113747.

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