It is important to recognise that low blood pressure can cause no symptoms at all, and is a common normal finding in young people and athletes. However, in some people, low blood pressure causes symptoms which can significantly interfere with their quality of life. These can include syncope (fainting), pre-syncope (near fainting, usually associated with feeling light-headed), sweating, tiredness, slow thinking (brain fog), nausea, visual blurring, hearing disturbances, headache, palpitations, neck pain, breathlessness and chest pain.
SOURCES: The Journal of the American Medical Association, May 21, 2003. Aram Chobanian, MD, dean, Boston University School of Medicine and chair of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure. Claude Lenfant, MD, director of the National Heart, Lung, and Blood Institute (NHLBI) of the National Institutes of Health. Edward Roccella, PhD, MPH, coordinator of the National High Blood Pressure Education Program at NHLBI. John Laragh, MD, Cardiovascular Hypertension Center at New York Hospital/Cornell University Medical Center and editor-in-chief of the American Journal of Hypertension. WebMD Medical News: "Diuretics Best for High Blood Pressure."
Stage 1 and Stage 2 hypertensions require therapy with anti-hypertensive drugs to bring down the blood pressure. Lifestyle modifications are also necessary, but often it is not sufficient for satisfactory control of blood pressure. Hypertension is often asymptomatic in the early course of disease. Symptoms like headache, lightheadedness, palpitations and easy fatigability may occur and chances of them being present increases with increasing blood pressure.
Hypertension is the most important preventable risk factor for premature death worldwide.[149] It increases the risk of ischemic heart disease,[150] strokes,[23] peripheral vascular disease,[151] and other cardiovascular diseases, including heart failure, aortic aneurysms, diffuse atherosclerosis, chronic kidney disease, atrial fibrillation, and pulmonary embolism.[11][23] Hypertension is also a risk factor for cognitive impairment and dementia.[23] Other complications include hypertensive retinopathy and hypertensive nephropathy.[27]
If elevated blood pressure levels are accompanied by diabetes, kidney disease, or cardiovascular disease, your doctor may suggest blood pressure medication as well lifestyle changes. If elevated levels are your only condition, lifestyle changes can help prevent blood pressure from rising. The following are lifestyle changes that may help lower blood pressure:

As mentioned earlier, blood pressure increases with age, beginning from infancy to older adulthood. Since most healthy babies and children are typically not at risk for blood pressure problems, most doctors do not check their blood pressure routinely. But, the normal BP range for all adults, regardless of their age, is considered to be lesser than 120/80.
It is important to recognise that low blood pressure can cause no symptoms at all, and is a common normal finding in young people and athletes. However, in some people, low blood pressure causes symptoms which can significantly interfere with their quality of life. These can include syncope (fainting), pre-syncope (near fainting, usually associated with feeling light-headed), sweating, tiredness, slow thinking (brain fog), nausea, visual blurring, hearing disturbances, headache, palpitations, neck pain, breathlessness and chest pain.
Various expert groups have produced guidelines regarding how low the blood pressure target should be when a person is treated for hypertension. These groups recommend a target below the range 140–160 / 90–100 mmHg for the general population.[13][99][100][101][102] Cochrane reviews recommend similar targets for subgroups such as people with diabetes[103] and people with prior cardiovascular disease.[104]
When the systolic pressure drops below 90 mm Hg and the diastolic pressure falls below 60 mm Hg, this is categorized as low blood pressure. Some people may have low pressure all the time and this may be normal for them. If they do not experience any other signs or symptoms, medical treatment may not be necessary for them. Low blood pressure becomes a concern when it is accompanied by noticeable symptoms, such as dizziness, fainting and, in severe cases, shock. When this occurs, people should seek medical attention to determine if an underlying condition may be responsible for their hypotension.

4. Find an exercise that works for you (and do it). Moving more can help reverse high blood pressure. One meta-analysis of 65 studies found regular exercise provides both an acute and longer-term reduction in blood pressure. Whether you’re an exercise novice or a conditioned athlete, these four strategies can help you create an effective workout plan to optimize health.

^ Mente, Andrew; O'Donnell, Martin; Rangarajan, Sumathy; Dagenais, Gilles; Lear, Scott; McQueen, Matthew; Diaz, Rafael; Avezum, Alvaro; Lopez-Jaramillo, Patricio; Lanas, Fernando; Li, Wei; Lu, Yin; Yi, Sun; Rensheng, Lei; Iqbal, Romaina; Mony, Prem; Yusuf, Rita; Yusoff, Khalid; Szuba, Andrzej; Oguz, Aytekin; Rosengren, Annika; Bahonar, Ahmad; Yusufali, Afzalhussein; Schutte, Aletta Elisabeth; Chifamba, Jephat; Mann, Johannes F E; Anand, Sonia S; Teo, Koon; Yusuf, S (July 2016). "Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies". The Lancet. 388 (10043): 465–75. doi:10.1016/S0140-6736(16)30467-6. PMID 27216139. 

The guidelines also outline very clearly when a diet-and-lifestyle approach is the recommended, first-line treatment, and when medications are simply just what you have to do. Thankfully, the decision is largely based on facts and statistics. For the elevated blood pressure category, medications are actually not recommended; rather, a long list of evidence-based, non-drug interventions are. What are these interventions? Things that really work: a diet high in fruits and vegetables (such as the DASH diet, which is naturally high in potassium); decreased salt and bad fats; more activity; weight loss if one is overweight or obese; and no more than two alcoholic drinks per day for men, and one for women. Simply changing what you eat can bring down systolic blood pressure by as much as 11 points, and each additional healthy habit you adopt can bring it down another four to five points.

Dehydration can sometimes cause blood pressure to drop. However, dehydration does not always cause low blood pressure. Fever, vomiting, severe diarrhea, overuse of diuretics and strenuous exercise can all lead to dehydration, a potentially serious condition in which your body loses more water than you take in. Even mild dehydration (a loss of as little as 1 percent to 2 percent of body weight) can cause weakness, dizziness and fatigue.
Excellent point! I can’t speak for anyone specifically, but I can say that generally, doctors make the worst patients. We don’t always follow the textbook guidelines nor abide by health recommendations. Then, there’s genetics, a pretty powerful force, and one over which we have little control. And, of course, there is just plain bad luck (or fate, finger of God, however you choose to describe it). So, many factors can come into play when a doctor gets diagnosed with what can otherwise be considered a preventable disease.
Early signs of pulmonary arterial hypertension can be related to the trouble you have getting blood to your lungs to get oxygenated. You might experience shortness of breath and a fast heart beat while doing activities that are otherwise routine, such as climbing stairs. You might also have chest pain, a reduced appetite, and pain in your chest or upper right portion of your abdomen.
As for when to check your blood pressure, the most important thing is to do it consistently the same time of the day (ask the doctor which time he prefers and also what time in relation to taking your medication). The following article has a lot of good information for someone just starting to monitor their blood pressure:
Most doctors do not make a final diagnosis of high blood pressure until they measure your blood pressure several times (at least 2 blood pressure readings on 3 different days). Some doctors ask their patients to wear a portable machine that measures their blood pressure over the course of several days. This machine may help the doctor find out whether a patient has true high blood pressure or what is known as “white-coat hypertension.” White-coat hypertension is a condition in which a patient’s blood pressure rises during a visit to a doctor when anxiety and stress probably play a role.
Obesity: As body weight increases, the blood pressure rises. Obesity is defined as having a body mass index (BMI) greater than 30 kg/m. A BMI of 25-30 kg/m is considered overweight (BMI=weight in pounds x 703/ height in inches). Being overweight increases the risk of high blood pressure. Healthcare professionals recommend that all individuals who are obese and have high blood pressure lose weight until they are within 15% of their healthy body weight.
Certain medications: A number of drugs can cause low blood pressure, including diuretics and other drugs that treat hypertension; heart medications such as beta blockers; drugs for Parkinson’s disease; tricyclic antidepressants; erectile dysfunction drugs, particularly in combination with nitroglycerine; narcotics and alcohol. Other prescription and over-the-counter drugs may cause low blood pressure when taken in combination with high blood pressure medications.
Unlike high blood pressure, low blood pressure is defined primarily by signs and symptoms of low blood flow and not by a specific blood pressure number. Some individuals routinely may have blood pressure numbers of 90/50 with no symptoms and therefore do not have low blood pressure. However, others who normally have higher blood pressures may develop symptoms of low blood pressure if their blood pressure drops to 100/60.
For example, in a hypertensive patient with asthma, it may be inadvisable to prescribe a beta blocker, as these drugs can aggravate that respiratory condition. Similarly, in patients prone to constipation (the elderly, for example) use of certain calcium channel blockers might best be avoided -- along with diuretics -- as both these classes of drugs can inhibit proper bowel function.
John P. Cunha, DO, is a U.S. board-certified Emergency Medicine Physician. Dr. Cunha's educational background includes a BS in Biology from Rutgers, the State University of New Jersey, and a DO from the Kansas City University of Medicine and Biosciences in Kansas City, MO. He completed residency training in Emergency Medicine at Newark Beth Israel Medical Center in Newark, New Jersey.
Do not attempt to lower extremely elevated blood pressure in yourself or someone else. While the goal is to reduce blood pressure before additional complications develop, blood pressure should be reduced over the course of hours to days, depending on severity. It is important not to lower blood pressure too quickly, because rapid blood pressure reductions can cut off the supply of blood to the brain, leading to brain damage or death.

Hypertension occurs in around 0.2 to 3% of newborns; however, blood pressure is not measured routinely in healthy newborns.[33] Hypertension is more common in high risk newborns. A variety of factors, such as gestational age, postconceptional age and birth weight needs to be taken into account when deciding if a blood pressure is normal in a newborn.[33]
"Having a healthy lifestyle really makes a difference in your life because you can avoid high blood pressure," said Dr. Mary Ann Bauman, an internist at Integris Baptist Medical Center in Oklahoma City. "If you do have high blood pressure, make sure take your medication. You may not necessarily have symptoms until your blood pressure gets really high."
A sudden fall in blood pressure can be dangerous. A change of just 20 mm Hg — a drop from 110 systolic to 90 mm Hg systolic, for example — can cause dizziness and fainting when the brain fails to receive an adequate supply of blood. And big plunges, such as those caused by uncontrolled bleeding, severe infections or allergic reactions, can be life-threatening.

There is no treatment available for the causes of portal hypertension. However, treatment can prevent or manage the complications. Diet, medication (nonselective beta-blockers), endoscopic therapy, surgery, and radiology procedures can all help in treating or preventing symptoms of portal hypertension. If these treatments are unsuccessful in treating symptoms, transjugular intrahepatic portosystemic shunt (TIPS) or distal splenorenal shunt (DSRA) are two procedures that may reduce pressure in the portal veins. Maintaining a healthy lifestyle may help to prevent portal hypertension.