Author : Dr Kate Garside
What causes low blood pressure? Signs, symptoms and advice.
This is for informational purposes only. For medical advice or diagnosis, consult a professional.
High blood pressure gets most of the attention when we discuss cardiovascular health in the UK. However, low blood pressure, known medically as hypotension, is also incredibly common. It can leave you feeling dizzy, constantly tired, or unsteady on your feet.
While a lower reading is not always a sign of poor health, understanding exactly what triggers these drops can help you decide when to seek medical advice and when to simply monitor your numbers at home.
Understanding your blood pressure readings
Blood pressure is measured in millimetres of mercury (mmHg) and is displayed as two distinct numbers. The systolic pressure measures the force of the blood against your artery walls when your heart beats. The diastolic pressure measures the resting phase between those beats.
A standard, healthy reading is roughly 120/80 mmHg. A reading of 90/60 mmHg or lower is typically classed as low blood pressure. For very active people and athletes, this lower number might just indicate an incredibly efficient cardiovascular system. For others, sudden drops or consistently low numbers accompanied by physical symptoms usually point to an underlying issue.
You can easily monitor your blood pressure at home with our automatic blood pressure monitor.
Common causes of low blood pressure
Dehydration
Failing to drink enough water directly reduces the volume of blood circulating in your body. This drop in volume naturally lowers your blood pressure. Hot weather, intense workouts, or recovering from a stomach bug can quickly lead to dehydration and subsequent lightheadedness.
Whether you've been battling a stomach bug, sweating through a workout, or simply forgot that water exists while deep in a work flow, dehydration happens to the best of us, including me. The good news is that mild to moderate dehydration is usually quick and straightforward to fix at home.
Actionable Tips for Rehydration
1. Take Small, Frequent Sips
If you are feeling nauseous or recovering from sickness, chugging a giant glass of water in one go will likely backfire. Instead, take small sips every few minutes. This gives your stomach a chance to absorb the fluid gradually without triggering a reflex to send it right back up.
2. Replace Lost Electrolytes
When you lose fluid through sweat, diarrhoea, or vomiting, you lose essential salts and minerals like sodium and potassium alongside water.
- Oral Rehydration Solutions (ORS): Sachets (such as Dioralyte) or electrolyte tablets mixed with water are the fastest way to restore balance.
- Mild Alternatives: Diluted fruit juice, diluted squash, or isotonic sports drinks can also help replenish basic sugars and salts if you don't have rehydration sachets on hand.
3. Eat Your Hydration
Fluids don't just come from a glass. High-water foods are a great way to rehydrate while giving your body gentle nutrition.
-
Fruits: Watermelon, strawberries, oranges, and melon. - Vegetables: Cucumbers, celery, tomatoes, and lettuce.
- Broths & Soups: Clear chicken or vegetable broth offers both fluid and necessary sodium.
What to Drink vs. What to Skip
| What to Choose | What to Limit or Skip |
| Water or diluted squash | Alcohol: Acts as a diuretic and further dehydrates your body. |
| Electrolyte / ORS drinks | Full-sugar fizzy drinks: High sugar levels can aggravate diarrhoea. |
| Skimmed or lower-fat milk | Excessive caffeine: Large amounts of coffee or energy drinks can irritate your stomach. |
The Quick Check: Look at the colour of your urine.
- Pale straw or clear: You are well-hydrated.
- Dark yellow or amber: You need to drink fluids soon.
When to seek medical help
Dehydration can escalate quickly, especially in young children and older adults. Seek immediate medical advice if you or someone else experiences:
- Severe dizziness, confusion, or disorientation
- Inability to pass urine for 8 hours or more
- Extreme lethargy or unresponsiveness
- A unusually rapid heartbeat or fast breathing
Orthostatic hypotension
This is the sudden drop in pressure you might feel when you stand up quickly from a bed or a chair. Gravity pulls your blood down towards your legs and feet. If your body does not adjust its heart rate quickly enough to compensate, you will feel a temporary wave of dizziness.
When should you be worried?
An occasional split-second feeling of lightheadedness when jumping out of bed is rarely a cause for concern. However, orthostatic hypotension can become dangerous if it leads to falls or stems from an unmanaged medical condition.
Schedule a GP appointment if:
- Episodes are becoming frequent, severe, or predictable.
- You experience unsteadiness that puts you at risk of falling.
- Symptoms started shortly after taking a new prescription medication.
- You feel consistently fatigued or weak alongside the dizzy spells as there may be another underlying medical condition like anaemia.
Seek emergency medical attention immediately if:
- You faint or lose consciousness, even for a few seconds.
- The lightheadedness is accompanied by chest pain, tightness, or severe shortness of breath.
- You experience sudden neurological symptoms, such as slurred speech, facial drooping, or limb weakness.
- The dizzy spells cause a fall resulting in head trauma or injury.
Red Flag Warning: Fainting (syncope) caused by orthostatic hypotension is a major cause of fractures and head injuries, particularly in older adults. Never ignore fainting spells.
Practical ways to prevent orthostatic hypotension
Most mild cases of postural hypotension can be managed or completely prevented with simple daily adjustments and physical manoeuvres.
1. Master the Slow Stand
- The Bedtime Pause: Before getting out of bed in the morning, sit on the edge of the mattress for 1 to 2 minutes before standing up completely.
- Physical Counter-Manoeuvres: Before standing, pump your feet up and down at the ankles, or clench your thighs and buttocks. Crossing your legs while standing can also help squeeze blood out of your lower limbs and back up towards your heart.
2. Adjust Your Fluid and Food Intake
- Stay Well Hydrated: Drink plenty of water throughout the day (aiming for 2 litres unless advised otherwise by your doctor). Keeping blood volume up is the most effective defence against drops in pressure.
- Eat Smaller, Frequent Meals: A large meal causes blood to rush to your digestive system (a process called postprandial hypotension). Opt for smaller, balanced meals lower in refined carbohydrates to prevent post-meal dizziness.
- Limit Alcohol: Alcohol relaxes blood vessels and acts as a diuretic, both of which severely worsen orthostatic drops.
3. Smart Daily Adjustments
-
Elevate the Head of Your Bed: Raising the head end of your bed by 10 to 15 degrees (using bed risers or blocks) reduces nighttime urine production and helps your nervous system adapt to gravity overnight.
- Wear Compression Hosiery: Graduated compression socks or tights exert gentle pressure on your calves and feet, preventing blood from pooling in your lower body.
- Avoid Hot Baths and Showers: Heat causes blood vessels to dilate (expand), making it much easier for blood pressure to plunge when you stand up out of a warm tub.
Prescription medications
Various daily medicines can lower your blood pressure as a secondary effect.
Diuretics (water pills), beta blockers, certain antidepressants, and treatments for Parkinson's disease are frequent culprits. You should always speak to your GP if you suspect your medication is affecting your daily life.
Pregnancy
During pregnancy, a woman's circulatory system expands rapidly to support the growing baby. This sudden expansion frequently results in lower blood pressure during the first two trimesters. It is usually harmless and resolves itself after childbirth.
From the very beginning of pregnancy, your body produces high levels of the hormone progesterone. One of progesterone's primary jobs is to relax the smooth muscle tissue throughout your body, which includes the walls of your blood vessels.
When these blood vessels relax and widen (a process called vasodilation), the resistance against the blood flow decreases. Think of it like turning on a garden hose but suddenly swapping it for a much wider pipe: the pressure inside drops.
How to Offset the Dizziness
While you cannot stop the physiological changes (and you would not want to, as they are essential for the baby), you can easily manage the side effects to keep yourself comfortable and safe.
- Sleep on Your Left Side: Lying on your left side shifts the weight of the uterus away from the large blood vessels on the right side of your spine, ensuring maximum blood flow to your heart and the placenta.
- Supercharge Your Hydration: Because your blood volume needs to expand so drastically, you need significantly more water than usual. Aim for at least 2 to 2.5 litres of water a day. If you are struggling to keep water down due to morning sickness, try electrolyte-rich drinks or taking small, continuous sips.
- Eat Small, Frequent Meals: Digesting a large meal requires a lot of blood to be diverted to your stomach, which can pull it away from your brain and cause a sudden dizzy spell (postprandial hypotension). Eating smaller meals every few hours keeps your blood sugar and blood pressure much more stable.
- Wear Maternity Compression Tights: These provide gentle, graduated pressure on your legs and ankles, preventing blood from pooling in your lower extremities and helping push it back up to your heart.
- Never Lock Your Knees: When standing for long periods, keep a slight, soft bend in your knees. Locking them restricts blood flow back up your legs.
If you ever feel faint whilst pregnant, immediately sit or lie down on your left side to prevent a fall and restore blood flow to your brain. Unsure if you're pregnant? Shop pregnancy tests here.
Dietary Deficiencies
Lacking essential vitamins, specifically folate and vitamin B12, stops your body from creating enough healthy red blood cells. This results in anaemia, a condition that limits oxygen delivery throughout your body and consequently lowers your blood pressure.
Think you might have anaemia? Shop our blood test meter here
Best Sources of Folate (Vitamin B9)
Folate is mostly found in plant-based foods. An easy way to remember folate sources is to think of "foliage", green, leafy vegetables are usually packed with it.
- Dark Leafy Greens: Spinach, kale, Brussels sprouts, cabbage, and broccoli.
- Legumes: Lentils, chickpeas, kidney beans, and black-eyed peas are among the densest plant sources.
- Fortified Foods: Many breakfast cereals, breads, and nutritional yeast are fortified with folic acid (the synthetic form of folate).
- Citrus Fruits & Avocado: Oranges, grapefruit, and avocados offer a solid daily boost.
Cooking Tip: Folate is a water-soluble vitamin that breaks down easily when heated. Steaming or microwaving vegetables preserves far more folate than boiling them in water.
Best Sources of Vitamin B12
Unlike folate, vitamin B12 occurs naturally almost exclusively in animal products. If you follow a plant-based or vegan diet, relying on fortified foods or supplements is essential.
- Organ Meats: Liver and kidneys are exceptionally high in B12.
- Fish & Shellfish: Clams, sardines, salmon, mackerel, and tuna.
- Red Meat & Poultry: Beef, lamb, and chicken.
- Dairy & Eggs: Milk, cheese, yoghurt, and whole eggs.
- Fortified Plant-Based Options: Plant milks, fortified breakfast cereals, and Marmite / nutritional yeast.
Practical Ways to Combine Folate & Vitamin B12 Daily
To make sure you hit your daily targets without overcomplicating your meals, try combining B12 and folate sources together:
| Meal Time | Combination Idea | Nutrients Provided |
| Breakfast | Poached eggs on wholewheat toast with wilted spinach | B12 (eggs) + Folate (spinach & wholewheat) |
| Lunch | Salmon salad with avocado, asparagus, and leafy greens | B12 (salmon) + Folate (avocado, asparagus, greens) |
| Dinner | Beef or lentil chilli served with a side of steamed broccoli | B12 (beef) or Folate (lentils & broccoli) |
| Vegan Alternative | Fortified cereal with fortified soya milk, topped with sliced banana | B12 (fortified milk/cereal) + Folate (cereal & banana) |
Important Note on Absorption & Supplements
Sometimes, anaemia is not caused by a lack of B12 or folate in your diet, but by your body's inability to absorb them properly. For example, pernicious anaemia is an autoimmune condition that prevents B12 absorption regardless of how much meat or dairy you eat. It's always worth consulting your GP if you are worried you might be anaemic.
Heart and Hormonal Issues
A very slow heart rate (bradycardia) or malfunctioning heart valves can restrict how effectively your heart pumps blood. Additionally, endocrine disorders such as Addison's disease, untreated thyroid issues, or severe hypoglycaemia can heavily influence your daily readings.
- Bradycardia (Slow Heart Rate): When the heart beats too slowly, it cannot pump enough oxygen-rich blood through your body each minute, causing overall blood pressure to drop.
- Heart Valve Problems: Faulty valves restrict or disrupt normal blood flow through the heart's chambers, reducing the total amount of blood pumped out with every beat.
- Addison's Disease: Damage to the adrenal glands reduces the production of cortisol and aldosterone, key hormones needed to regulate salt balance, fluid volume, and blood pressure. Shop cortisol test kits.
- Untreated Thyroid Issues: An under-active thyroid (hypothyroidism) slows your metabolism and weakens heart contractions, while an overactive thyroid (hyperthyroidism) can cause erratic heart rhythms that trigger sudden drops in pressure. Shop under-active thyroid test kits.
- Severe Hypoglycaemia: Abnormally low blood sugar levels cause blood vessels to relax and dilute crucial hormones, triggering a sudden dip in blood pressure along with dizziness and confusion. Shop blood sugar test kits.
Medical Emergencies
Sudden and severe drops in pressure are incredibly dangerous and require emergency medical intervention. Major internal bleeding, severe allergic reactions (anaphylaxis), or severe blood infections (septic shock) cause life threatening crashes in blood pressure.
Symptoms You Should Not Ignore
Low blood pressure is generally only treated if it is actively causing symptoms. The most frequent indicators include:
- Unsteadiness or dizziness when standing
- Blurred or fading vision
- Chronic fatigue and lack of energy
- Nausea and poor concentration
- Fainting spells
If low blood pressure is ever accompanied by cold and clammy skin, a weak but rapid pulse, confusion, or rapid breathing, you must seek emergency medical care immediately.
Monitoring Your Health at Home with Valuemed
Keeping a close eye on your cardiovascular health is the best way to understand your body. If you suffer from occasional dizzy spells or simply want peace of mind, tracking your readings at home is incredibly beneficial.
At Valuemed, we specialise in providing reliable and accurate medical supplies to UK households and professionals. Investing in a clinical grade home blood pressure monitor from Valuemed.co.uk allows you to record highly accurate daily readings. By logging your results over a few weeks, you and your GP can easily identify trends, adjust medications safely, and manage your long term health with complete confidence.