Allergies are generally defined as the body’s reaction to any foreign substance in the body, which is usually harmless but is perceived by the immune system as a threat to the body, and which can therefore elicit reactions from the body, ranging from harmless ones like sneezing or rashes, to more life-threatening ones like anaphylactic shocks and other hormonal imbalances. It has long been observed that sometimes, alongside the onset of an allergic reaction (which is the medical term for the body’s actions towards getting rid of the allergen), it usually persists in the form of high blood pressure, which in itself is a life-threatening situation for many, especially individuals already suffering from heart conditions. So, with this passage, we take a look at whether allergies could cause high blood pressure?

The first thing you need to know regarding allergens (agents that can trigger an allergic reaction in the body) is that they can be any substance that is considered foreign by the body’s natural defense, the immune system. Once any allergen, for instance, pollen or dust (which are relatively harmless for the body) enters the body, this triggers the white blood cells to protect the vital organs against said pathogen.

This can lead to some conditions, which are known as allergic reactions and these can range from simple sneezing or rashes that do not persist for more than a day to more life-threatening conditions where a trip to the hospital gets crucial. Can these allergies cause high-blood pressure? 

High-blood pressure is the condition where the pressure of the blood flow against the walls of the arteries is increased, to the point where repeated pressure can weaken the walls, wear out the heart and its valves and can lead to arterial breakdown, which can be deadly in the long term.

As such, high blood pressure has been rightly called a ‘silent killer’, because although at first, it may not sound and feel worse, but as the condition deteriorates, it can become life-threatening really quick. Therefore, there is no wonder as to why people are concerned if allergies can cause high blood pressure.

How Can Allergies Cause High Blood Pressure?

No beating around the bush; yes, allergies can cause high blood pressure, but not directly, rather indirectly. For you to understand this indirect causation, you need to understand the basic working of the immune system, and how its reaction to the allergen is breeding grounds for complications like high blood pressure.

Our immune system combats foreign pathogens which enter the body through white blood cells, which are part of the greater lymphatic system. These white blood cells work by producing antibodies, which do the dirty work and fight off the pathogen.

This whole process of the immune system producing antibodies to fight off pathogens is called inflammation, which, if you have spent some time around a doctor’s clinic anytime recently or have spent any amount of time with a heart patient, you will know that it causes high blood pressure in the long run. How? Again, lets understand some advanced biology.

Our blood flows all across the body. However, the pathogen which enters the body (through, say, an open wound site) usually is located in the bloodstream. This causes your blood flow to get increased, since more blood will mean more new antibodies needed to fight off the pathogen. When your body increases its blood flow, the arteries and blood-carrying vessels all over the body are constricted, meaning they get smaller in diameter. Now comes a bit of physics.

When you decrease the diameter of a tube-like structure, the liquid flowing in it will have its passage speed increased proportionally. For example, if you were to halve the size of the hose you were using to water the garden, the water coming out of the end will have its pressure doubled. It has an interesting physics name, this phenomenon, but for the sake of sticking to physiology of the human body, just understand that when blood flow increases, the arteries are constricted, leading to them getting hard and increasing the pressure of the blood.

This condition, if left untreated and unchecked, will have a lot of detrimental effects on the cardiac system, and trust us, high blood pressure then becomes the least of any person’s worries.

Are Allergies Responsible For High Blood Pressure?

No. Because the process of inflammation is a natural one, just like a fever. The body has to produce antibodies to fight the pathogen (even if it’s just an allergen). Once it does, it increases the blood flow, which causes the arteries to harden up and increase the blood pressure. But understand that once the allergen has been taken care of and the allergic reaction has subsided, the blood flow returns to normal, the arteries dilate back to their normal diameter and the blood pressure returns to normal, which in most cases (in a normal human) is 120/80 mmHg. 

Remember when we talked about the blood pressure ‘going unchecked and untreated’? Well, this is where the problem emerges. Anyone who has allergies will experience a temporary increase in blood pressure, which is natural and normal, since the blood vessels are latent enough to withstand the pressure of the blood pushing against it for some time.

The problem is, in most cases, it is left unchecked and untreated, and the more this becomes a norm and a routine, the more the blood pressure spikes and drops again and again, which contributes to a permanent increase in blood pressure, eventually turning into a full-blown case of high blood pressure. 

So, now that you have a deeper and more informed knowledge about allergies, inflammation and how the latter contributes to high blood pressure, you can understand why allergies are not the main cause of high blood pressure, rather it indirectly causes conditions contributing to high blood pressure. But the most important part in this whole passage is that it is preventable, meaning it’s not something that comes naturally at the risk of an allergy.

The most important factors are exercise and diet; a good combination of both will ensure that the LDL or bad cholesterol level stays on the down and does harden the arteries, which will in turn increase the blood pressure. Exercise, on the other hand, will ensure that the heart stays healthy enough and the blood vessels latent enough to accommodate any temporary increase in blood flow and pressure.