Antihistamines And Weight Gain: How Do They Relate?

Antihistamines And Weight Gain

Obesity has been one of the most serious health concerns troubling people in various regions of the world for some time. Obesity can be attributed to various reasons, such as lifestyle habits, unhealthy diet, and dependency on multiple medicines.

Various medical researchers have proven a positive relationship between the consumption of various drugs and the possibility of gaining weight over time. Several drugs such as antihistamines, are associated with increasing your weight gain. 

Different studies have been conducted so far in order to understand the relationship between antihistamines and obesity. Let us explore this dimension one by one.

What Are Antihistamines?

Antihistamines are the types of drugs that are used for relieving the symptoms of pain and allergies. They are used for curing runny noses, watery eyes, stomach infections, sinus, insomnia, and even motion sickness. These medicines are helpful to control the production of histamine. 

Antihistamines

Scientific Relationship Between Weight Gain And Antihistamines

Studies have repeatedly proved that the prescription of H1 antihistamines is associated with an increased risk of obesity in Western countries such as the United States of America. This weight gain has increased the weight, Body-Mass Index, waist circumference, and insulin levels in the human body.

The proportion and gravity of the effects have been different in different people depending on their age and gender. According to the latest studies, this effect can be experienced by kids, adolescents, and even adults. 

There are different types of antihistamines which the medical practitioners prescribe. Cetirizine is one of the most commonly prescribed drugs. These antihistamines are an active metabolite of hydroxyzine.

It possesses minor properties of the sedatives. It not only increases the energy expenditure of the body but also increases the tendency to gain weight. The consumption of antihistamines is unsuitable for the body and therefore generates different physical changes. The various changes which must be induced in this respect have been given in the following way:

➡️Changes in the Insulin changes 

The consumption of antihistamines is likely to increase the body’s insulin levels. The increase in glucose levels raises the adipose retention potential of the body, which ultimately results in gaining weight.

The National Health Antihistamine Neurological Eternal Survey of 2015 to 2016 has been able to establish a positive relationship between increasing weight and increasing levels of insulin in the body. Antihistamine receptors are also responsible for increasing glucose uptake in humans and animals. 

Once the insulin levels are increased, there is an increase in the levels of leptin. Leptin is an important enzyme for regulating the metabolism and metabolic activities of the body. These metabolic rates can determine the effectiveness of the body in burning excessive fat into energy.

The higher the proportion of fat burnt, the higher the possibility of losing weight. However, the increase in the level of leptin promotes abnormalities. The potential of the metabolic system is impaired due to increased leptin levels.

As a result, the breakdown of excessive insulin to energy does not take place, and the amount of insulin in the human blood increases. 

➡️Changes in the waistline circumference

In the latest study conducted by the Michigan School of Medicine in 2018, it was discovered that increasing consumption of antihistamine receptors elevates the waist circumference of the body.

The fat tissues get deposited around the waist and hence cause different types of health problems associated with the spinal cord and backbone arise. Antihistamines are known for disrupting the flow of blood as well. This makes it difficult for the person to make movement. 

Are Antihistamines Safe?

Antihistamines come in various forms and compositions. However, all of the types have some common features. These antihistamines can be very helpful in relieving pain and allergy symptoms by controlling the production of histamine.

Histamine is released by the body when the cells are infected by abnormalities caused by allergies caused by bacteria, malaria, and viruses. 

Antihistamines and safety

However different types of bodily changes can affect the production of histamine and make it disproportionate. In order to balance the functions, these antihistamines are consumed. These drugs are beneficial to cure problems, but at the same time, it is important to understand that they are not without side effects and leave an incurable impact on the human body. 

The antihistamines are not completely safe. The consumption of antihistamines such as Allegra and Zyrtec has been clinically tested to cause weight gain in all adults above 18. Let us understand more about the relationship between the consumption of antihistamines and weight gain.

Reasons For Weight Gain Due To Antihistamines

Antihistamines are responsible for making humans lethargic and tired. Medications such as Benadryl, Allegra, and Zyrtec are responsible for causing various side effects such as nausea, diarrhea, headache, back pain, and lethargy.

As a result of these side effects, the tendency of the human body to gain weight increases. It is evident from a recent study that has been conducted so far.  A study by the American School of Medical Sciences in 2020 proved that the higher consumption of antihistamines is associated with obesity.

The study was conducted on around 900 people exposed to prolonged antihistamines consumption. The study revealed that people with a history of consumption of antihistamines experienced a 10% increase in weight, body mass index, and waist circumference.

In fact, this weight gain was experienced in adults and among children between the ages of 16-18. Studies have repeatedly proved that children are two times more likely to be subjected to obesity if they consume antihistamines than children who do not consume such drugs.  


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Antihistamines are referred to as second-generation medications for reducing the metabolic rate of the body. As already mentioned, they block various receptors across the joints which induces numbness and decreases the activities within the body.

The rate of combustion of calories also decreases significantly. As a result, the consumed calories are converted to fat directly. There is also a reduction in the energy levels of the body due to these changes. A person on antihistamines is likely to become much more docile and lethargic. The urge to undertake physical activities is mitigated. 

There are several reasons why antihistamines are likely to cause weight. 

  • Firstly antihistamines usually decrease the metabolic rate of the body. As a result, the tendency of the body to convert the digested food into energy decreases, and this gets converted to fat. 
  • In addition, these drugs also trigger appetite, and a person is likely to feel hungry most of the time. This increases the daily diet, and a person consumes more calories than ever. 
  • It is also noteworthy that antihistamines make a person lethargic and tired. There is a considerable decrease in the energy levels of the person over the period of time. Therefore, the activity of the person reduces to a great extent, and therefore, the reduction of physical activity is yet another reason for increased weight.
  • A person feels sleepy most of the time. Therefore, it is not feasible for such a person to stay active. Antihistamines must be strictly regulated and must be consumed only on the prescription of the doctor. 

According to some scientists, the effect of antihistamines on weight gain is not direct but rather indirect. The consumption of these drugs is likely to increase the cholesterol levels in the body. The levels of insulin and blood sugar also increase over a period of time.

The rise of sugar levels can further raise the risk if cardiovascular changes. A lot of dietary changes are introduced as a result of these health issues. These side effects are responsible for increasing the possibility of weight gain and hence produce long-term side effects on the body.

Final Take

Antihistamines are a specific class of drugs that are basically used to treat allergy symptoms. However, excessive consumption of these drugs is not at all suitable for the human body. They are reported to induce weight gain, and as a result, the tendency of the human body to stay fit reduces to a great extent.

This is one of the most important aspects which must be taken into accord. The prescription of these drugs, therefore, should be strictly regulated. These drugs are very beneficial for the human body only if used according to the dose prescribed. Therefore, the prescription of the doctors plays an important role in this category.

Therefore, consumption must be strictly regulated at every cost. This is the need of the hour so that the global ratios of weight gain reduce. The dependency on these drugs cannot be reduced to zero but the same can be regulated according to the proportion actually required by the body for effective functioning. 


Also read: Lamictal And Weight Gain: Does It Really Happen?


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