Can Aspirin Lower Blood Pressure?

High blood pressure is a serious condition to be suffering from. If left uncontrolled for an extended period of time, it can be a major risk factor for many serious chronic conditions, such as coronary heart disease and chronic kidney disease.

When high blood pressure is diagnosed, the physician will sometimes prescribe medication to keep it under control, alongside suggesting lifestyle factors that may naturally reduce blood pressure.

Aspirin is an anti-inflammatory and pain-relieving drug that has been shown to have therapeutic effects in the prevention of heart attacks and strokes. But is low-dose aspirin also effective for lowering blood pressure?

What is high blood pressure?

Blood pressure is the pressure used to pump blood out of the heart and around the body. It is measured as systolic (the pressure when the heart exerts the blood out) over diastolic (the pressure when the heart is at rest between forcing the blood out). It is written as systolic/diastolic. 

For the average adult, normal blood pressure is between 90/60 mmHg and 120/80 mmHg.

High blood pressure is generally considered to be 140/90mmHg or higher. It is usually caused by a variety of lifestyle choices, such as:

• Smoking
• Frequent overconsumption of alcohol
• Being overweight
• Lack of exercise

Suffering from high blood pressure for an extended period of time increases the risk of developing serious chronic conditions such as kidney disease or heart disease.¹ 

With it being a major risk factor for cardiovascular disease, it's important to maintain healthy blood pressure in order to prevent further complications. 

What is aspirin?

Aspirin is an over-the-counter NSAID (non-steroidal anti-inflammatory drug) that is primarily used for pain relief, or reducing fever and inflammation. It is also sometimes used in the treatment or prevention of heart attacks, strokes, and angina. The use of aspirin for these conditions should only be done under medical supervision. 

It is a salicylate, a derivative of salicylic acid. It works by reducing factors in the body that cause pain, inflammation, and fever-like symptoms.²

How can aspirin lower blood pressure?

Aspirin acts as a blood thinner in order to reduce blood pressure. It does this by affecting the platelets, which are the blood’s clotting mechanism. Platelets are a type of cell in the blood that cause clotting by clumping together. Aspirin prevents this action, thus reducing the chances of clot production and thinning the blood, leading to reduced blood pressure. This also prevents the formation of unwanted blood clots that may lead to a heart attack or stroke. Daily aspirin therapy is based on this idea.

Daily Aspirin Therapy

Daily aspirin therapy is a treatment option prescribed by some physicians in order to decrease the risk of heart attacks or strokes. It involves taking a low dose of aspirin daily. This is dependent on a range of factors and can involve complications given the side effects of long-term aspirin use. 

Daily aspirin therapy is used as either a primary or secondary prevention. Primary prevention refers to when you have never had a stroke, a heart attack, any surgical treatment relating to those events (such as a coronary bypass, coronary angioplasty or stents), or any blocked arteries in your body. The aspirin is then taken to reduce the chance of strokes or heart attacks occurring. This is only used if you’re at high risk for a heart attack, such as if you’ve had heart surgery, chest pain or heart disease.³ It is also sometimes prescribed to pregnant women when they’re at risk of high blood pressure (pre-eclampsia), miscarriage, or if they have had complications with previous pregnancies.⁴

In comparison, secondary prevention refers to aspirin therapy undertaken following an episode of stroke, heart attack, or vascular disease. The daily aspirin is to prevent further episodes. 

It is extremely important that you don’t attempt daily aspirin therapy without the guidance of a physician, as there are many factors to be considered before this treatment option, such as age, medical history, general health, and any current medication being taken.³

Side Effects of Aspirin

Much like all medications, aspirin can also cause side effects in some individuals, with some being more common than others. The common side effects that occur in approximately 1% of users include mild indigestion and bleeding more easily than normal.

Serious side effects of aspirin are rare but can still occur. Contact your doctor if you experience any of these symptoms:

• Coughing up blood or seeing blood in your urine, faeces, or vomit
• Yellowing of the skin or the whites of your eyes (jaundice)
• Dark urine
• Pain in the joints of your hands or feet
• Swelling in the hands or feet (water retention)⁵

Stomach ulcers 

Aspirin can also cause stomach ulcers if taken for a prolonged period of time, or in large doses. If you’ve previously suffered from stomach ulcers, your physician may not recommend aspirin therapy. Instead, they might prescribe paracetamol, as it’s less harsh on your stomach. 

Allergic reaction 

In extremely rare cases, individuals may suffer anaphylaxis (serious allergic reaction) to aspirin. It is important to call 999 or go to A&E straight away if this occurs.⁴

Effectiveness on low blood pressure

Low-dose aspirin therapy is usually undertaken in conjunction with blood pressure medication in order to increase effectiveness. Common classes of blood pressure medications include:

• ACE inhibitors: Angiotensin-converting enzyme (ACE) inhibitors work by relaxing blood vessels in order to reduce blood pressure. Common examples include lisinopril, ramipril, and perindopril.
• ARBS: Angiotensin-2 receptor blockers work in a similar manner to ACE inhibitors and tend to be used if ACE inhibitors cause significant side effects. Common examples include losartan, valsartan, candesartan, and olmesartan.
• Calcium channel blockers: these drugs reduce pressure by widening blood vessels. Common examples include amlodipine, felodipine, and nifedipine. 
• Diuretics: also known as water pills, these work by removing excess water and salt from the body via urine and tend to be used as an alternative to calcium channel blockers if they cause significant side effects. Common examples are indapamide and bendroflumethiazide.
• Beta-blockers: used as a last resort drug option for high blood pressure, beta blockers reduce blood pressure by making the heart beat slower and with less force. Beta-blockers are considered less effective than other medication options for lowering blood pressure. Common examples include atenolol and bisoprolol.⁶ 

Risk and Prevention

The risks of aspirin are mentioned above in the side effects. The majority of the side effects are minor and tend to occur in a small number of individuals. However, there are rare and serious consequences, such as anaphylaxis.

It is important to note that low-dose daily aspirin is different to over-the-counter aspirin for pain relief. This means that the risks associated with the different treatment courses of aspirin vary. 

Low-dose aspirin therapy should only be attempted under the guidance of a physician so that you are given the right dose for you and to make sure that there are no contraindications between any other medications you may take. 

Natural ways of lowering blood pressure

Your blood pressure can also be reduced naturally by making some lifestyle changes:

• Physical activity: getting daily physical activity at a moderate intensity can help to reduce blood pressure. It is recommended to get 150 minutes of exercise per week.
• Maintaining a healthy weight: calculate your BMI (body mass index) to find out if you fall within the healthy weight range. If you are overweight, try and reduce your weight in a safe and healthy way. 
• Eating a balanced diet: try to eat a diet enriched with plenty of fruits and vegetables, as well as limiting processed foods.
• Reduce salt intake: avoid processed foods which contain a lot of salt, and try to decrease the amount of salt you add to your food. This typically involves consuming less than 6g (approximately a teaspoon) per day.
• Decrease alcohol consumption: stay within the recommended alcohol limits and consider keeping a diary to track your drinking habits.⁷

Summary 

Leaving high blood pressure uncontrolled can make you seriously ill, so it is important to get the condition under control as quickly and effectively as possible. Some doctors may prescribe long-term aspirin therapy as a primary or secondary prevention. However, it is important to note that low-dose aspirin therapy is not recommended for everyone, and doctors will take factors such as age, medical history, and general medical health into account before prescribing this treatment. Lifestyle changes can also be effective in helping lower blood pressure.