In some cases, medication is necessary to lower blood pressure. It really depends on how high your blood pressure is and other risk factors, like family history of heart attack and stroke. Based on these risks and your current lifestyle, your doctor may prescribe common hypertension medications like lisinopril, amlodipine, losartan, and hydrochlorothiazide.
Metformin can also cause impaired kidney and liver functions. This can happen if a patient takes an overly large dose of the drug, which can make it hard for the liver to process it. Kidneys will also be affected. In extreme cases, it is possible for the kidney and liver to fail completely, leading to a lot of complications in the patient. Be very careful about dosage when it comes to metformin.
Headaches strike over 90% of adults each year. You may be able to wait out some and let them pass, but others may be a sign that your body is asking you to take action. There is a chance that your headache could be a symptom of high blood pressure. If there are no other causes of your headache, you should ask your healthcare provider about getting your blood pressure checked.
In the past, most attention was paid to diastolic pressure; but nowadays it is recognized that both high systolic pressure and high pulse pressure (the numerical difference between systolic and diastolic pressures) are also risk factors. In some cases, it appears that a decrease in excessive diastolic pressure can actually increase risk, due probably to the increased difference between systolic and diastolic pressures (see the article on pulse pressure). If systolic blood pressure is elevated (>140 mmHg) with a normal diastolic blood pressure (<90 mmHg), it is called "isolated systolic hypertension" and may present a health concern.[41][42]

Metformin is prescribed for people with type 2 diabetes. Like any medication, it carries the risk of side effects. The most common side effects from metformin include nausea, diarrhea, gas and upset stomach. These are most likely when you first start taking it and usually go away on their own. Until they do, you should try to take your metformin with a meal. You can also try reducing the amount you take for a few days and gradually increasing it until you’ve reached the amount your doctor has prescribed for you.

High blood pressure, also known as hypertension (See blood pressure chart below) is called the “silent killer” for a reason — there are no obvious symptoms but it can result in heart attack, stroke and even death. The good news is there’s a lot you can do to maintain healthy blood pressure or get back to one, often without the need for medications.

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.

Blood pressure is the force of your blood pushing against the walls of your arteries. Each time your heart beats, it pumps 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 called diastolic pressure.
Blood pressure fluctuates from minute to minute and normally shows a circadian rhythm over a 24-hour period,[12] with highest readings in the early morning and evenings and lowest readings at night.[13][14] Loss of the normal fall in blood pressure at night is associated with a greater future risk of cardiovascular disease and there is evidence that night-time blood pressure is a stronger predictor of cardiovascular events than day-time blood pressure.[15] Blood pressure varies over longer time periods (months to years) and this variability predicts adverse outcomes.[16] Blood pressure also changes in response to temperature, noise, emotional stress, consumption of food or liquid, dietary factors, physical activity, changes in posture, such as standing-up, drugs, and disease.[17] The variability in blood pressure and the better predictive value of ambulatory blood pressure measurements has led to some authorities, such as The National Institute for Health and Care Excellence (NICE) in UK, to advocate the use of ambulatory blood pressure as the preferred method for diagnosis of hypertension.[18]

Hypertension results from a complex interaction of genes and environmental factors. Numerous common genetic variants with small effects on blood pressure have been identified[34] as well as some rare genetic variants with large effects on blood pressure.[35] Also, genome-wide association studies (GWAS) have identified 35 genetic loci related to blood pressure; 12 of these genetic loci influencing blood pressure were newly found.[36] Sentinel SNP for each new genetic locus identified has shown an association with DNA methylation at multiple nearby CpG sites. These sentinel SNP are located within genes related to vascular smooth muscle and renal function. DNA methylation might affect in some way linking common genetic variation to multiple phenotypes even though mechanisms underlying these associations are not understood. Single variant test performed in this study for the 35 sentinel SNP (known and new) showed that genetic variants singly or in aggregate contribute to risk of clinical phenotypes related to high blood pressure.[36]
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them: 

If you plan to have surgery or a radiology procedure that uses iodine contrast, you should stop taking metformin 48 hours before the procedure. These procedures can slow the removal of metformin from your body, raising your risk of lactic acidosis. You should resume taking metformin after the procedure only when your kidney function tests are normal.
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]
Primary (or essential) hypertension is when the cause is unknown. The majority of hypertension cases are primary. When there is an underlying problem such as kidney disease or hormonal disorders that can cause hypertension, it is called secondary hypertension. When it is possible to correct the underlying cause, high blood pressure usually improves and may even return to normal.