Approximately 90 to 95 percent of the cases of hypertension, or high blood pressure, are considered chronic. This means that the problem has developed and worsened over an extended period of time. The remaining cases of hypertension are diagnosed as acute, which means the symptoms of high blood pressure appear suddenly and change or worsen rapidly. There are several common causes of acute hypertension.

Sodium

Sodium, or salt, intake is one of most common causes of spikes in blood pressure. Because excess sodium results in fluid retention within the body, extra force is exerted on blood vessels which, in turn, increases blood pressure.

Nicotine

Nicotine, as found in cigarettes, causes blood vessels to constrict and therefore increases resistance to blood flow. The blood pressure of a smoker should be checked 30 minutes after a high initial reading.

Alcohol

Alcohol stimulates the sympathetic, i.e., fight or flight, part of the central nervous system. The stimulation of this aspect of the nervous system results in a sudden spike in blood pressure.

Caffeine

While it is unclear why caffeine causes a rapid, sharp rise in blood pressure, Dr. Sheldon Sheps states that it may block a hormone responsible for keeping arteries widened. He goes on to mention that others theorize that caffeine stimulates the adrenal gland, which then releases adrenaline and results in acute hypertension.

Medications

Some non-steroidal, anti-inflammatory drugs such as ibuprofen, aspirin and naproxen may lead to temporary increases in blood pressure. Like sodium, these medications cause the body to retain fluid and exert pressure on blood vessels. Decongestants, such as pseudoephedrine, and some migraine prescriptions may lead to acute hypertension as well.

Pregnancy

Pregnancy-induced hypertension may transpire in otherwise healthy women after the 20th week of pregnancy. The increase in blood pressure is due to the body's retention of water. Blood pressure will return to normal after childbirth.

Source:

faqs.org: Hypertension

MayoClinic.com: How Does Caffeine Affect Blood Pressure

Livestrong.com: Acute Hypertension Causes

Resource:

National Library of Medicine: Hypertension