Valium and xanax are benzodiazepines (colloquially called benzos) that help to calm anxiety, as well as treating other disorders. The generic name for valium is diazepam and xanax is alprazolam. While Xanax is only available in pills, Valium is also available in liquid form and can be taken intravenously. Valium also has a considerably longer half-life. Both drugs work by enhancing the effect of the neurotransmitter GABA in the brain. Both are unsafe for pregnant women; Xanax is not advisable for people with narrow-angle glaucoma or who are taking Sporanix or Nizoral, while Valium should not be used by people with myasthenia gravis, severe liver disease, narrow-angle glaucoma, severe breathing problems or sleep apnea.
|Trade names||Xanax||Diastat, Valium|
|Prescribed for||Management of acute symptoms of anxiety disorders, panic disorders, anxiety caused by depression||Anxiety disorders, alcohol withdrawal, muscle spasms, seizures, panic attacks, insomnia|
|Pregnancy cat.||D (US) [Unsafe during pregnancy; see article for details]||D (US) i.e., not safe during pregnancy.|
|Dependence liability||High (addictive)||Medium-low if used as prescribed|
|Side effects||Drowsiness, dizziness, blurred vision, headache, memory problems, trouble concentrating, sleep problems, swelling in limbs, muscle weakness, lack of balance and coordination, slurred speech, upset stomach, nausea, vomiting, sweatiness, dry mouth etc.||Memory problems, drowsiness, dizziness, feeling restless, muscle weakness, nausea, constipation, drooling or dry mouth, slurred speech, blurred vision, mild skin rash and loss of interest in sex.|
|Half-life||Immediate release: 11.2 hours; Extended release: 10.7–15.8 hours||20–100 hours (36-200 hours for main active metabolite desmethyldiazepam)|
|Restrictions||Should not be used by people with narrow-angle glaucoma or who are taking Sporanix or Nizoral.||Should not be used by people with myasthenia gravis, severe liver disease, narrow-angle glaucoma, severe breathing problems or sleep apnea.|
|Forms||Tablets (0.25, 0.5, 1 or 2mg)||Liquid, tablets (2mg, 5mg, 10mg)|
|Legal status||POM (UK) Schedule IV (US)||Prescription Only (S4) (AU) Schedule IV (CA) CD (UK) Schedule IV (US) Schedule IV (International)|
|Metabolism||Hepatic, via Cytochrome P450 3A4||Hepatic - CYP2C19 - CYP3A4|
Valium can be supplied in liquid or tablet form. Tablets can be 2mg, 5mg or 10mg.
Xanax is available in 0.25mg, 0.5mg, 1mg and 2mg tablets. The 2mg tablets are multi-scored and can be divided.
Valium is used to treat anxiety disorders, alcohol withdrawal symptoms, and muscle spasms. It can also be used in the treatment of seizures.
Xanax is used to treat anxiety disorders, panic disorders, and anxiety associated with depression.
Mechanism of action
Valium and Xanax will have different levels of effectiveness for different individuals. A study in 1981 found that Xanax was more effective than Valium at treating anxiety. A study from University of Iowa in 1990 found that Valium and Xanax were equally effective at treating panic disorders. 
In the video below, Dr. Scott Bea of the Cleveland Clinic discusses when and why doctors prescribe medication for anxiety and how benzodiazepines, such as Xanax and Valium, are fast-acting alternatives to SSRIs (e.g., Lexapro or Zoloft).
For adults with anxiety disorders, 2mg to 10mg of valium can be prescribed 2 to 4 times a day, depending on the severity of symptoms. Valium can only be used for a short time. It should not be taken for more than 12 weeks without a doctor’s advice, because it is habit forming.
For adults with anxiety disorder, initial doses of Xanax are of 0.25mg to 0.5mg, three times daily. This dose may be increased up to 4mg in divided doses. Dosage must be decreased gradually.
Common Valium side effects include memory problems, drowsiness, dizziness, feeling restless, muscle weakness, nausea, constipation, drooling or dry mouth, slurred speech, blurred vision, mild skin rash and loss of interest in sex. More serious side effects can include confusion, depression, hyperactivity, shallow breathing, tremor and loss of bladder control.
Common Xanax side effects include drowsiness, dizziness, blurred vision, headache, memory problems, trouble concentrating, sleep problems, swelling in hands and feet, muscle weakness, lack of balance and coordination, slurred speech, upset stomach, nausea, vomiting, increased sweating, dry mouth, stuffy nose, appetite or weight changes, and loss of interest in sex. More serious side effects include depressed mood, confusion, chest pain, tremor, seizure and jaundice.
Restrictions and Drug Interactions
Valium should not be used by anyone allergic to diazepam or those with myasthenia gravis, severe liver disease, narrow-angle glaucoma, severe breathing problems or sleep apnea. It is also not safe for pregnant women. It should not be mixed with alcohol.
Xanax also should not be used by people allergic to benzodiazepines or by women who are pregnant. Those with narrow-angle glaucoma and those who are taking Sporanix or Nizoral should also not take Xanax. It should not be mixed with alcohol.
When use is discontinued abruptly after a long period, there is a risk of withdrawal with both xanax and valium. Withdrawal symptoms include anxiety, seizures, hallucinations, shallow breathing, respiratory distress, numbness, and — in extreme but rare cases — coma. Instead, it is recommended that dosage be reduced gradually (usually 0.5mg every three days).
Like Zoloft, Prozac, Lexapro and other SSRI, Valium and xanax are both prone to abuse and dependence. Those with legitimate health conditions who use these types of medications may be dependent upon it without it being abuse. However, others may engage in substance abuse to acquire these drugs illegally. Signs of abuse include willingness to do something illegal to acquire it, taking it without medical reason, and needing to take a larger dose to get the same results as before (this is called tolerance).
- Anxiolytic efficacy of alprazolam compared to diazepam and placebo - NIH.gov
- Diazepam versus alprazolam for the treatment of panic disorder - NIH.gov
- Valium - drugs.com
- Xanax - drugs.com
- Valium - rxlist.com
- Effects of valium use
- Valium Abuse Symptoms, Signs and Addiction Treatment - Coalition Against Drug Abuse
- Xanax - rxlist.com