Understanding why your blood pressure runs low can take away some of the uncertainty, especially if a reading has come back lower than expected. There are several common causes, ranging from simple dehydration to underlying conditions worth ruling out.
Disclaimer: The information in this article is for general guidance only and does not constitute medical advice. Always consult a qualified healthcare professional about your own health and do not make changes to treatment or medication based solely on what you read here.
Key Takeaways
- Common causes include dehydration, blood loss, heart conditions and certain medications.
- Endocrine problems and nutritional deficiencies can also play a role.
- Age and existing health conditions increase the likelihood of hypotension.
- Not every case has an identifiable cause.
- A GP can help investigate persistent or severe low readings.
Common Causes of Low Blood Pressure
Low blood pressure can have several causes, including dehydration, certain medicines, blood loss, hormonal changes, heart problems and some underlying health conditions. It can also occur when standing up suddenly, known as postural hypotension. Here are the most frequent causes behind a low reading.
Dehydration
Not drinking enough fluid reduces your blood volume, which directly lowers blood pressure, making dehydration one of the most common and easily fixed causes.
Blood Loss
Significant blood loss, whether from injury, surgery or internal bleeding, reduces the volume your heart has to work with, which can cause a sharp drop in pressure.
Heart Conditions
Certain heart problems, including very slow heart rates or valve issues, can prevent your heart from pumping enough blood to maintain normal pressure.
Medication
Some medications, particularly those for high blood pressure itself, as well as certain antidepressants and diuretics, can lower blood pressure as a side effect. Never stop medication without speaking to your GP.
Endocrine Problems and Nutritional Deficiencies
Conditions affecting the thyroid or adrenal glands, along with deficiencies in vitamin B12 or folate, can also contribute to low blood pressure by affecting how your body regulates fluid and blood cell production.
Risk Factors to Be Aware Of
Here’s who tends to be more prone to it.
Who’s More Likely to Experience It
Older adults, people with diabetes, and those on multiple medications tend to be more prone to hypotension. Pregnancy can also temporarily lower blood pressure, particularly in the first half.
Knowing the possible cause behind a low reading helps guide what to do next, whether that’s simply drinking more water or booking a GP visit for further investigation. Our [Symptoms of Low Blood Pressure] page can help you work out whether what you’re feeling fits the picture.
Frequently Asked Questions
Here are quick answers to some common questions about causes of low blood pressure.
What causes low blood pressure?
Common causes include dehydration, blood loss, heart conditions, certain medications and endocrine problems. In many cases, no single clear cause is found.
Can dehydration alone cause low blood pressure?
Yes, dehydration reduces blood volume and is one of the most common and reversible causes of a temporary drop in blood pressure.
Does age affect the risk of low blood pressure?
Yes, older adults are generally more prone to hypotension, partly due to changes in blood vessel function and a higher likelihood of being on multiple medications.
Can medication cause low blood pressure?
Yes, several types of medication, including some blood pressure treatments themselves, can lower blood pressure as a side effect. Speak to your GP or pharmacist if you suspect this.
