Allergic reaction (anaphylaxis): Anaphylactic shock is a sometimes-fatal allergic reaction that can occur in people who are highly sensitive to drugs such as penicillin, to certain foods such as peanuts or to bee or wasp stings. This type of shock is characterized by breathing problems, hives, itching, a swollen throat and a sudden, dramatic fall in blood pressure.

In hypertensive emergency, there is evidence of direct damage to one or more organs.[27][28] The most affected organs include the brain, kidney, heart and lungs, producing symptoms which may include confusion, drowsiness, chest pain and breathlessness.[26] In hypertensive emergency, the blood pressure must be reduced more rapidly to stop ongoing organ damage,[26] however, there is a lack of randomized controlled trial evidence for this approach.[28]
The value of routine screening for hypertension in children over the age of 3 years is debated.[90][91] In 2004 the National High Blood Pressure Education Program recommended that children aged 3 years and older have blood pressure measurement at least once at every health care visit[89] and the National Heart, Lung, and Blood Institute and American Academy of Pediatrics made a similar recommendation.[92] However, the American Academy of Family Physicians[93] supports the view of the U.S. Preventive Services Task Force that the available evidence is insufficient to determine the balance of benefits and harms of screening for hypertension in children and adolescents who do not have symptoms.[94]

Orthostasis literally means standing upright. Orthostatic hypotension, or postural hypotension, is defined as a decrease in systolic blood pressure of at least 20 mm Hg or at least 10mm Hg within 3 minutes of the patient standing. If orthostatic hypotension is present, the client may be at risk of falls and should be closely supervised with ambulation or advised to call for assistance with activity.

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.
Calcium channel blockers are drugs that reduce the movement of calcium into cells of the heart and vessels. This reduces the strength of heart contractions and relaxes the arteries, allowing them to remain more open, lowering blood pressure. Side effects of calcium channel blockers can include heart palpitations, dizziness, swollen ankles, and constipation. Calcium channel blockers can be taken alone or with other blood pressure medications. They should be taken with food or milk. Because of potential interactions, those taking calcium channel blockers should avoid alcohol and grapefruit juice.

Blood pressure is the force of your blood pushing against the walls of your arteries. Each time your heart beats, it pumps out blood into the arteries. Your blood pressure is highest when your heart beats, pumping the blood. This is called systolic pressure. When your heart is at rest, between beats, your blood pressure falls. This is the diastolic pressure. Your blood pressure reading uses these two numbers. Usually they're written one above or before the other, such as 120/80. If your blood pressure reading is 90/60 or lower, you have low blood pressure.