Many things can cause your blood pressure to be too low, ranging from normal pregnancy-induced changes to dangerous underlying conditions, like heart problems or hormone disturbances. In some instances, what causes low blood pressure could be a simple case of dehydration brought on by vomiting, intense exercise, or the overuse of diuretics. In fact, even mild dehydration can trigger symptoms such as dizziness, confusion, or other symptoms of low blood pressure.
With age, comes an increased risk for systolic hypertension which can be aggravated by severe atherosclerosis. According to one study, the diuretic chlorthalidone (Hygroton) had significant benefit in elderly patients with systolic hypertension. Along with a diuretic, some calcium channel blockers, ACE inhibitors and angiotensin II receptor blockers may also be good choices. However, beta blockers may not be as effective for hypertension in those over 60; though they may be good choices if co-existing heart disease is present. It also may be preferable in elderly patients to give two high blood pressure medications at a low dose versus one at a higher dose.
Some high blood pressure medications initially cause drowsiness, dizziness, and lightheadedness. Some even cause fainting on the first dose. The body usually adjusts to the effects of these medications and the side effects disappear. Consuming alcohol during the early phase of antihypertensive treatment could be risky because alcohol can also cause dizziness, drowsiness, and lightheadedness.
Postural (orthostatic) hypotension is a sudden drop in blood pressure when an individual stands up from a sitting, squatting, or supine (lying) position. When a person stands up, gravity causes blood to settle in the veins in the legs so that less blood returns to the heart for pumping, and, as a result, the blood pressure drops. The body normally responds automatically to the drop in blood pressure by increasing the rate and narrowing the veins to return more blood to the heart. In patients with postural hypotension, this compensating reflex fails to occur, resulting low blood pressure and its symptoms. Postural hypotension can occur in persons of all ages but is much more common among the elderly, especially in those on medications for high blood pressure and/or diuretics. Other causes of postural hypotension include dehydration, adrenal insufficiency, prolonged bed rest, diabetes, and certain rare neurological syndromes (for example, Shy-Drager syndrome) that damage the autonomic nerves.
For older people, often the first number (systolic) is 130 or higher, but the second number (diastolic) is less than 80. This problem is called isolated systolic hypertension, which is due to age-related stiffening of the major arteries. It is the most common form of high blood pressure in older people and can lead to serious health problems (stroke, heart disease, eye problems, and kidney failure) in addition to shortness of breath during light physical activity, lightheadedness upon standing too fast, and falls. Isolated systolic hypertension is treated in the same way as regular high blood pressure (130 or higher for the first number, or 80 or higher for the second number) but may require more than one type of blood pressure medication. If your doctor determines that your systolic pressure is above a normal level for your age, ask how you can lower it.
Low blood pressure is also known as hypotension. This is usually defined in an adult as a systolic recording of less than 90 mmHg, although it has been suggested that for elderly people, below 110 mmHg is a more appropriate definition. Blood pressure and heart rate are controlled by the autonomic nervous system (the nervous system that controls bodily functions that we do not have to think about).                                                                                                                                                                                                
Your doctor may diagnose you with high blood pressure when you have consistent systolic readings of 140 mm Hg or higher or diastolic readings of 90 mm Hg or higher. Based on research, your doctor may also consider you to have high blood pressure if you are an adult or child age 13 or older who has consistent systolic readings of 130 to 139 mm Hg or diastolic readings of 80 to 89 mm Hg and you have other cardiovascular risk factors.
If you have been diagnosed with high blood pressure, it is important that you continue your treatment plan. Following your treatment plan, getting regular follow-up care, and learning how to monitor your condition at home are important. Let your doctor know if you are planning to become pregnant. These steps can help prevent or delay complications that high blood pressure can cause. Your doctor may adjust your treatment plan as needed to lower or control your high blood pressure.
Many mechanisms have been proposed to account for the rise in peripheral resistance in hypertension. Most evidence implicates either disturbances in the kidneys' salt and water handling (particularly abnormalities in the intrarenal renin–angiotensin system)[61] or abnormalities of the sympathetic nervous system.[62] These mechanisms are not mutually exclusive and it is likely that both contribute to some extent in most cases of essential hypertension. It has also been suggested that endothelial dysfunction and vascular inflammation may also contribute to increased peripheral resistance and vascular damage in hypertension.[63][64] Interleukin 17 has garnered interest for its role in increasing the production of several other immune system chemical signals thought to be involved in hypertension such as tumor necrosis factor alpha, interleukin 1, interleukin 6, and interleukin 8.[65]
Normal blood pressure can differ substantially between breeds but hypertension in dogs is often diagnosed if systolic blood pressure is above 160 mm Hg particularly if this is associated with target organ damage.[170] Inhibitors of the renin-angiotensin system and calcium channel blockers are often used to treat hypertension in dogs, although other drugs may be indicated for specific conditions causing high blood pressure.[170]

About This Image: Person receiving a blood pressure test. Medical research shows that as we age blood pressure rises slightly to accommodate an increased demand of oxygen and nutrients. It is completely natural for the first number (systolic) to be 100 plus our age. A recent study by a group of UCLA researchers came very close to corroborating Dr. Piette's guide for blood pressure of 100 plus your age for men, subtracting 10 for women, and this is after this rule had been in use for five or more decades. Are we now being taught that Dr. Piette's guide for blood pressure is wrong merely for drug company profit?
High blood pressure is classified as either primary (essential) high blood pressure or secondary high blood pressure.[5] About 90–95% of cases are primary, defined as high blood pressure due to nonspecific lifestyle and genetic factors.[5][6] Lifestyle factors that increase the risk include excess salt in the diet, excess body weight, smoking, and alcohol use.[1][5] The remaining 5–10% of cases are categorized as secondary high blood pressure, defined as high blood pressure due to an identifiable cause, such as chronic kidney disease, narrowing of the kidney arteries, an endocrine disorder, or the use of birth control pills.[5]

It has been shown that meditation and other relaxation techniques can help lower blood pressure. Yoga, tai chi, and breathing exercises can also help reduce blood pressure. It's best when these are combined with changes in diet and exercise. Tell your doctor if you are taking any herbal remedies, since some of these preparations can actually raise blood pressure or interact with your blood pressure medications. The following are supplements that may lower blood pressure:


A single lower-than-normal reading is not cause for alarm, unless you are experiencing any other symptoms or problems. If you experience any dizziness, lightheadedness, nausea or other symptoms, it’s a good idea to consult with your healthcare provider. To help with your diagnosis, keep a record of your symptoms and activities at the time they occurred.

The cause for hypertension is not always known, although it can develop as a result of other health conditions including: sleep apnea, kidney problems, and thyroid issues. Beyond chronic health conditions, risk factors for hypertension include age, the amount of salt you eat, being overweight or obese, using tobacco, drinking excessively, not exercising, and having too little potassium in your diet.


A reduction from 8% to 6% of cardiovascular events is known as an absolute risk reduction of 2%. This may seem small, but the translation is not small when applied to real world people. This can be understood more easily as something called “number needed to treat” which is calculated by 1 divided by the absolute risk reduction. In this case, an absolute risk reduction of 2% translates to a “number needed to treat” of 50 (1 divided by 0.02 = 50). This means that 50 people need to have a BP down to < 120/80 in order for 1 cardiovascular event to be prevented. In the context of many other things we do in our life (medical treatment or not), this is really good!
It occurs more often in older people who are taking a lot of medication. However, it can cause symptoms in younger people. There may be underlying medical conditions such as joint hypermobility syndrome, diabetes, parkinson’s disease, addison’s disease or autonomic failure. Dehydration, hunger, low body weight and deconditioning (being out of shape/unfit) can reduce blood pressure.
The primary symptoms of malignant hypertension is a blood pressure of 180/120 or higher and signs of organ damage. Other symptoms of malignant hypertension include bleeding and swelling of blood vessels in the retina, anxiety, nosebleeds, severe headache, and shortness of breath. Malignant hypertension may cause brain swelling, but this symptom is very rare.
Hypertension in African-Americans tends to occur earlier in life and tends to be more severe. Plus, some medications that work to lower blood pressure in other ethnicities may have limited effect on African-Americans. Thiazide diuretics (such as HCTZ) or a calcium channel blocker are recommended first choices along with the possible add-on of a second drug from either the ACE inhibitor class or the angiotensin II receptor blocker group.
On physical examination, hypertension may be associated with the presence of changes in the optic fundus seen by ophthalmoscopy.[22] The severity of the changes typical of hypertensive retinopathy is graded from I to IV; grades I and II may be difficult to differentiate.[22] The severity of the retinopathy correlates roughly with the duration or the severity of the hypertension.[20]
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