Summary: Does Diazepam Lower Blood Pressure?
Diazepam, a type of benzodiazepine, is primarily used to treat anxiety, seizures, and muscle spasms. While it's not typically used as a primary treatment for high blood pressure, it can indirectly lower blood pressure by reducing activity in the sympathetic nervous system, which is linked to high blood pressure. However, it's important to consult with a healthcare professional before using diazepam for lowering blood pressure as there are risks of adverse events, such as respiratory depression and bradycardia.
What is Diazepam?
Diazepam, also known by the brand name Valium, is a benzodiazepine medication. Similar to other benzodiazepines, it is known to relieve anxiety, promote sleep or sedation, prevent seizures, and relax muscles [1, 2].
Diazepam works by enhancing the effect of a neurotransmitter called gamma-aminobutyric acid (GABA) in the central nervous system. GABA is an important inhibitory neurotransmitter, which means it reduces neural activity. By enhancing the effect of GABA, diazepam helps to treat mental health symptoms, calm abnormal overactivity in the brain, and alleviate symptoms of overactivity in the limbic system (anxiety disorders and/or a panic attack), whole brain (epilepsy), motor cortex, and basal ganglia (muscle spasms) [2].
Diazepam is also commonly prescribed for the management of severe alcohol withdrawal symptoms. It can prevent some of the severe physiological symptoms of alcohol withdrawal, which include anxiety, seizures, muscle spasms, or delirium [2].
The adult dosage can depend on the condition but ranges from 2-10mg. Although diazepam is effective and safe to use if you have been prescribed diazepam, it can lead to mild to moderate side effects. These include impaired motor coordination, dizziness, mood changes and/or slurred speech, meaning one should not drive after taking diazepam. It is also easy to become dependent on diazepam as your brain adapts to increased levels of GABA stimulation, and this consequently increases the risks of overdose [3].
What is Blood Pressure?
The terms 'high blood pressure' and 'low blood pressure' are used fairly often. But what is blood pressure, and what does it mean when it is high or low?
Blood pressure is an essential physiological measurement taken in clinics and at home. It is defined as the force exerted by your heart on the walls of your blood vessels in millimetres of mercury (mm Hg).
When taking a blood pressure reading, you will see two numbers. These correspond to the systolic and diastolic pressure [4]. Systolic blood pressure, the top number, measures the pressure on blood vessels when your heart contracts to pump blood out to your body. Diastolic blood pressure, the bottom number, measures the pressure on blood vessels between heartbeats while your heart is at rest and refilling with blood returning from your body [4]. This is the interval preceding the pump of blood.
What happens when blood pressure is too low or too high?
It's essential to manage your blood pressure as both hypotension (low blood pressure) and hypertension (high blood pressure) can lead to disruptive symptoms and even chronic health problems. Hypotension can cause symptoms like dizziness, brain fog or fainting and, in severe cases, damage organs by depriving them of blood flow and oxygen. Hypertension, on the other hand, can increase the risk of heart disease and damage to the arteries, leading to blood clots and, consequently, stroke or heart attacks, vision loss, kidney failure, and stroke [5].
Can Diazepam Lower Blood Pressure?
Diazepam, a type of benzodiazepine, has been found to have a hypotensive effect, meaning it can lower blood pressure [6]. This is likely due to diazepam reducing activity in the sympathetic nervous system, also known as the fight-or-flight nervous system. Furthermore, diazepam did not affect heart rate, indicating that the reduction in blood pressure was due to changing the neural activity supplying the heart and arteries.
However, it's important to note that diazepam can also increase blood pressure variability. A study found that diazepam significantly increased the standard deviation of systolic, diastolic, and mean blood pressure, cardiac output, and total peripheral resistance [7]. Cardiac output measures the force exerted by the heart over some time, and peripheral resistance is the counterforce exerted by the blood vessels.
In a systematic review and meta-analysis, benzodiazepines, including diazepam, were found to be comparable to standard hypertension drugs, such as ACE inhibitors, in reducing systolic and diastolic blood pressure in patients with hypertension [8]. Notable, benzodiazepines were linked to increased muscle weakness. Whether benzodiazepines are effective over a long period remains to be investigated.
However, the effects of diazepam on blood pressure can vary depending on the individual and the context. For instance, in a study involving healthy young adults, diazepam increased heart rate at night without affecting blood pressure [9]. This was attributed to reduced heart rate control by the vagus nerve, which regulates heart rate.
In conclusion, while diazepam can lower blood pressure, its effects can vary and may also increase blood pressure variability and heart rate. Therefore, it should only be used when prescribed by a healthcare provider for a specific medical condition.
How Does Diazepam Lower Blood Pressure?
Diazepam significantly reduces muscle sympathetic nerve activity, decreasing systolic and mean blood pressure [6]. It also potentiates GABAergic synaptic transmission, which can acutely increase resting beat-to-beat blood pressure variability. This is because GABAergic synaptic transmission regulates the activity of the vagus nerve, which in turn controls the activity of the heart muscle. Reducing activity in the vagus nerve by GABA leads to reduced control from the vagus nerve on the heart and respiratory muscles, leading to lower blood pressure, heart rate, and even respiratory depression, recognized as shallow breathing.
This potentiation of GABAergic transmission is associated with a significant increase in cardiac output and total peripheral resistance, which can contribute to the overall decrease in blood pressure [7].
Furthermore, diazepam has been found to facilitate reflex bradycardia, a reflex that slows the heart rate in response to a short-term increase in the pressure within the arteries. These paradoxical reactions may extend to the mechanism of how diazepam lowers blood pressure [10].
In summary, diazepam lowers blood pressure primarily through its central action on the nervous system, reducing muscle sympathetic nerve activity, potentiating GABAergic transmission, and facilitating reflex bradycardia.
Summary: Does Diazepam Lower Blood Pressure?
To summarise, yes, diazepam does lower blood pressure. However, it is now known whether there are adverse reactions if diazepam is taken for a long time, which could lead to trouble breathing, mood changes, or kidney problems [2]. Always follow the advice of your prescribing healthcare professional and look out for adverse reactions in the initial weeks of taking diazepam. If you experience symptoms of your blood pressure being too low, seek medical help immediately.