Blood pressure medications: Everything you need to know

Medications for high blood pressure are vital for helping to prevent a range of complications, including heart disease and stroke.

This article outlines the various blood pressure medications along with their associated side effects and risks.


blood pressure medication
Blood pressure medications may cause different side effects.

Excess salt can cause a buildup of fluid within the blood vessels, which raises blood pressure. Diuretics help the body eliminate excess salt and water by increasing urine output.

Possible side effects of diuretics include:

  • weakness
  • dizziness or light-headedness
  • heightened sensitivity to sunlight
  • rashes
  • muscle cramps
  • vomiting
  • diarrhea
  • constipation
  • low blood pressure
  • electrolyte imbalances

People taking diuretics may also experience a decreased libido, though this is less common.

Some medications can interact with diuretics, so a person should speak to a doctor about all of the drugs they are taking. Drugs that may interact with diuretics include:

Diuretics may not be suitable for people who tend to become dehydrated quickly. They can also make the following conditions worse:


Beta-blockers reduce blood pressure by blocking the effects of certain stress hormones, such as epinephrine.

Blocking these hormones slows down the nerve impulses traveling through the heart. As a result, the heart rate slows down and pumps blood less forcefully around the body.

Some side effects of beta-blockers may include:

Less common side effects include:

  • slow heartbeat
  • wheezing or difficulty breathing
  • swelling of the hands or feet
  • rash or itchy skin
  • insomnia
  • depression
  • low blood pressure

Some drugs and medications can change the effectiveness of beta-blockers. These include:

  • alcohol
  • caffeine
  • other blood pressure medications
  • cough and cold medications, including antihistamines and decongestants
  • insulin and some oral medications for diabetes
  • allergy shots
  • medicines to treat asthma, chronic bronchitis, emphysema, or chronic obstructive pulmonary disease (COPD)
  • some antidepressants

Beta-blockers may not be suitable for people with the following conditions or problems:

ACE inhibitors

woman outdoors with flu or cold infection coughing
A side effect of ACE inhibitors is a dry cough.

ACE (angiotensin-converting enzyme) is an enzyme that causes the body’s blood vessels to narrow, which leads to an increase in a person’s blood pressure.

ACE inhibitors lower blood pressure by blocking ACE, thereby relaxing the blood vessels and allowing blood to flow more freely.

A dry cough is the most common side effect of ACE inhibitors.

Less common side effects include:

  • loss of taste
  • a metallic taste in the mouth
  • loss of appetite
  • an upset stomach
  • diarrhea
  • constipation
  • headaches
  • tiredness and fatigue
  • feeling dizzy or lightheaded
  • skin that is sensitive to sunlight
  • low blood pressure

Medications that may interact with ACE inhibitors include:

  • diuretics
  • other blood pressure medications
  • medications and supplements containing potassium

People who have any of the following medical conditions should speak to a doctor before taking ACE inhibitors:

  • diabetes
  • heart disease
  • lupus
  • kidney disease
  • allergies to other medications

ACE inhibitors may also be unsuitable for people who have had a heart attack, and those who have received a kidney transplant.

Angiotensin II receptor blockers

Angiotensin II is an enzyme that narrows the blood vessels. Angiotensin II receptor blockers (ARBs) block the enzyme’s path to specific receptors, which allows the blood vessels to remain open.

Headaches and dizziness are the most common side effects of ARBs. Less common side effects include:

The following medications can increase or decrease the effect of ARBs:

  • diuretics
  • medications and supplements containing potassium
  • other blood pressure medications
  • some heart medications
  • over the counter medicines for allergies, colds, and flu

ARBs may not be suitable for people who have previously had a bad reaction to ACE inhibitors. They may also not be suitable for people with the following conditions:

Calcium channel blockers

Calcium causes the smooth muscles of the heart and arteries to contract more strongly.

Calcium channel blockers slow the entry of calcium into these muscles, which reduces the strength of the contractions and lowers the blood pressure.

Common side effects of calcium channel blockers include:

  • tiredness
  • flushing
  • swollen feet or ankles

Less common side effects include:

  • palpitations
  • nausea
  • dizziness
  • shortness of breath
  • upset stomach
  • constipation
  • rash or itchy skin

Drinking grapefruit juice while taking some calcium channel blockers can increase the risk of side effects.

Calcium channel blockers may interact with the following medications and supplements:

  • diuretics
  • other blood pressure medications
  • some heart medications, such as antiarrhythmics and digitalis
  • some eye medications

People taking more than 60 milligrams per day of some calcium channel blockers may experience low blood sugar levels.

Also, calcium channel blockers may not be suitable for people with the following conditions:

  • very low blood pressure
  • heart failure or other conditions affecting the heart or blood vessels
  • kidney or liver disease
  • depression


man with a headache sat on his sofa
Headaches are a possible side effect of alpha-blockers.

Certain hormones in the body, such as norepinephrine, can bind to chemical receptors called alpha-receptors. When this happens, the blood vessels narrow and the heart pumps blood faster, causing a rise in blood pressure.

Alpha-blockers reduce blood pressure by preventing norepinephrine from binding to alpha-receptors. This relaxes the blood vessels, which allows blood to flow more freely.

Possible side effects of alpha-blockers include:

  • rapid heart rate
  • a drop in blood pressure when standing up
  • dizziness
  • headaches
  • nausea
  • feeling tired, weak, or lethargic
  • disturbed sleep
  • skin rash or itchiness
  • loss of bladder control in women
  • erectile dysfunction in men

Other substances that lower blood pressure may cause a dangerous drop in blood pressure when taken alongside alpha-blockers. These substances include:

  • alcohol
  • medications containing benzodiazepine or barbiturates
  • other blood pressure medications

Alpha-blockers may make the following medical conditions worse:

Alpha-2 receptor agonists

Similar to alpha-blockers, these drugs lower blood pressure by preventing the release of norepinephrine.

Alpha-2 receptor agonists may cause the following side effects:

  • tiredness
  • feeling faint or dizzy after standing up
  • slow heart rate
  • anxiety
  • a headache
  • dry mouth
  • nausea
  • upset stomach
  • constipation
  • fluid retention
  • erectile dysfunction

Alpha-2 receptor agonists may react with some anesthetics and other blood pressure medications.

Combined alpha- and beta-blockers

A doctor may prescribe a drug that has both alpha- and beta-blocker activity. The alpha-blocker activity decreases the narrowing of blood vessels, while the beta-blocker activity slows the heart rate, causing it to pump blood less forcefully.

Doctors usually give combined alpha- and beta-blockers in an intravenous (IV) drip to people experiencing a hypertensive crisis. This is when blood pressure rises rapidly to a dangerously high level.

Doctors may also prescribe combined alpha- and beta-blockers for people who are at high risk of heart failure.

People may experience the side effects of both alpha- and beta-blockers.

Some types of combined alpha- and beta-blockers may interact with the following medications:

  • insulin
  • digoxin
  • some general anesthetics

They may also not be suitable for people with the following conditions:

  • asthma
  • severe bradycardia (slow heart rate)
  • liver disease
  • decompensated heart failure
  • diabetes
  • allergies to other medications
  • pheochromocytoma

Central agonists

Central agonists lower blood pressure by preventing the brain from sending signals to the nervous system to increase heart rate and constrict blood vessels.

As a result, the heart pumps blood less forcefully, and blood vessels remain open.

Central agonists can cause the following side effects:

  • feeling faint or weak when standing
  • slow heart rate
  • drowsiness or lethargy
  • anemia
  • dizziness
  • headaches
  • sleep disturbances
  • fever
  • dry mouth
  • an upset stomach or nausea
  • constipation
  • swollen legs or feet

The following side effects may also occur, but are less common:

  • depression
  • anxiety
  • erectile dysfunction

The following substances can cause a person’s blood pressure to drop too low when combined with central antagonists:

  • alcohol
  • sleeping pills and anti-anxiety medications containing benzodiazepines and barbiturates

Central agonists may make the symptoms of the following medical conditions worse:

Peripheral adrenergic inhibitors

doctor speaking with patient
If another blood pressure medication is ineffective, a doctor may prescribe PAIs.

Peripheral adrenergic inhibitors (PAIs) block the neurotransmitters in the brain that cause blood vessels to constrict.

Blocking these receptors allows the blood vessels to stay relaxed and open, lowering a person’s blood pressure.

Doctors usually prescribe PAIs only if other blood pressure medications have been ineffective.

There are several types of PAI, and the side effects differ between types. Possible side effects include:

  • nasal congestion
  • dry mouth
  • a headache
  • heartburn
  • diarrhea
  • lightheadedness, dizziness, or weakness when standing
  • fainting
  • erectile dysfunction

Some PAIs may interact with the following substances:

  • alcohol
  • asthma medications
  • diuretics
  • other blood pressure medications

Additionally, people who are taking tricyclic antidepressants and intend to come off these medications should speak to a doctor. Stopping these medications too quickly while taking certain PAIs can cause a dangerous drop in blood pressure.

Some types of PAIs may not be suitable for people with certain medical conditions, including:

  • congestive heart failure
  • diseases of the vascular system
  • asthma
  • peptic ulcers
  • fluid retention
  • pheochromocytoma
  • depression
  • ulcerative colitis

Direct-acting vasodilators

Vasodilators, or blood vessel dilators, relax and widen the walls of the blood vessels, allowing blood to flow through them more easily. Direct-acting vasodilators specifically target the arteries.

The two main types of direct-acting vasodilator are hydralazine hydrochloride and minoxidil.

Minoxidil is the more potent of the two drugs. Doctors usually prescribe it to people with persistent and severe high blood pressure.

Hydralazine hydrochloride may cause the following side effects, which usually subside within a few weeks of beginning treatment:

  • heart palpitations
  • headaches
  • swelling around the eyes
  • joint pain

Possible side effects of minoxidil include:

  • weight gain due to fluid retention
  • excessive hair growth, in rare cases

The following drugs may enhance the effects of vasodilators:

  • diuretics and other blood pressure medications
  • medications for erectile dysfunction, such as sildenafil (Viagra), tadalafil (Cialis), or vardenafil (Levitra)

Taking erectile dysfunction medications in combination with a vasodilator can cause a life-threatening drop in blood pressure.

Some types of vasodilators may not be suitable for people with the following conditions:

Risks during pregnancy

Some blood pressure medications are not safe to take during pregnancy due to the risk to the pregnant woman or unborn child. Some medications may be suitable during specific trimesters, while others pose risks throughout pregnancy.

Women who are pregnant or planning on getting pregnant should talk to their doctor about treatment options for high blood pressure.


There are many types of blood pressure medications. Which one a doctor prescribes will depend on the underlying cause of a person’s high blood pressure, as well as their existing conditions and other regular medications.

Anyone experiencing long-term or intolerable side effects from a blood pressure medication should speak to a doctor, who may be able to prescribe an alternative.