Do Certain Over the Counter Drugs have any Effect on the Body?

I am an avid user of allergy medicine. Ever since I was about ten, I have been developing new allergies for things that I love to eat. For example, around the age of twelve, I realized I had developed an allergy for peaches—my favorite fruit at the time. Over the years I have developed even more allergies for more and more foods. To make a long story short, I am constantly taking Benadryl, a common allergy medicine, to mitigate my allergies. Because I am frequently taking Benadryl, I decided to look into it and asked myself a few questions: “Does Benadryl have any negative effects on my body or brain? If so, what are those negative effects? What is it in Benadryl that helps people to fall asleep and how does this work?”

After doing some research, I found my answer. Yes! According to various studies done, over the counter drugs and pills such as Benadryl are actually linked to Dementia and Alzheimer’s disease. Well, I was not expecting to find something as shocking as that, but I did have an idea that taking Benadryl as often as I do is probably not the best for me.

Benadryl, as defined by, is an antihistamine. Diphenhydramine blocks the effects of the naturally occurring chemical histamine in the body.

The null hypothesis of this study is that over the counter drugs such as Benadryl do not actually have any effects on the human body/brain. The alternative hypothesis is that drugs such as Benadryl do, in fact, have effects on the body/brain. The question here seems to be is there a correlation between over the counter drugs and dementia?

According to the Fischer Center for Alzheimer’s Research Foundation, the longer you take the medication or drug, the greater you are at risk of diseases such as Alzheimer’s disease. Other than Benadryl, the studies have focused on antidepressant drugs and antihistamines (used in the treatment of allergies). Apparently, certain medications are recognized for blocking a specific brain chemical called acetylcholine. Acetylcholine transmits nerve signals throughout the brain and nervous system.Another well known risk of the drugs is severe damage in particular features of cognition, which has been demonstrated in single-dose experimental studies. The drugs that are associated with dementia and Alzheimer’s are known as “anticholinergic agents.” These specific drugs are most commonly taken for things ranging from bladder problems to allergies and mood disorders. There have been various studies done on whether or not specific drugs are linked to dementia and Alzheimer’s, but the study performed by researchers at Group Health and University of Washington was the first to show a dose-dependent relationship, which meant that taking the drugs for longer actually increased dementia risk.

To do the study, researchers at Group Health and the University of Washington examined medical and pharmacy records from 3,434 men and women who were involved in the Adult Changes in Thought study (ACT). The ACT was an ongoing study of brain aging and dementia in the Seattle area. Participants of the study were 65 and up and did not have dementia at the start of the study.

The researchers evaluated the participants every two years for signs of dementia, over a period of more than seven years. After the study was done, researchers found that overall, long-term use of the drugs significantly increased the risk of developing dementia, including Alzheimer’s disease. After the study, alternative drugs were recommended to patients that did not have anticholinergic effects. A similar study suggests that a person taking specific drugs for more than 3 years would have a greater risk for dementia.

After reading into multiple studies done on whether or not certain drugs are related to dementia and Alzheimer’s disease, I am still unsure as to whether or not my findings will change my habit of constantly taking Benadryl. While reading, I wondered if a possible third variable could be the fact that certain diseases might run in the family. Many of the studies did not focus only on Benadryl, but focused also on other drugs including antidepressant drugs. I do not have to worry about the negative effects for those drugs, but if others are taking antidepressants along with certain allergy medicines, they might want to start taking alternative drugs to reduce their risks of getting dementia or Alzheimer’s disease. I always find it interesting to see the correlations between certain things and the fact that Benadryl is actually shown to be linked to dementia blows my mind!



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3 thoughts on “Do Certain Over the Counter Drugs have any Effect on the Body?

  1. Dylan Huberman

    This is an unfortunate connection since I also take daily allergy medication. I use Zyrtec (Cetirizine) to combat my allergies to Strawberries, Penicillin, Biaxin and Ibuprofen. Since I have been pretty sick recently, I have also been taking Sudafed (Pseudoephedrine) and Flonase (Fluticasone) to reduce allergy symptoms. It would be very interesting to know if these medicines have also been put through a study similar to the one these scientists conducted with Benadryl. The medicines I’m taking are working very well as we speak and have worked well for me in the past and may work as effective alternatives if the active ingredient in Benadryl could be as damaging as the study you describe gets when taken at such a high frequency. Take a look at the link beneath this comment if you would like to read up on the alternatives to Benadryl I just mentioned.

  2. Akhil Dharmavaram

    I have never had to take antihistamines on a regular basis so I have never really wondered about the negative effects of continuous Benadryl use. I definitely learned something new from your post. After reading Mya’s comment, something worth looking into is developing a tolerance to antihistamines. It could potentially fatal to people if they start switching over to a different alternative drug and then switch back to their previous dosage of Benadryl. Here is a list of other drugs that can cause dementia in the long run:

  3. Mya Legend Avant

    I have to wonder if this study suffers from the file drawer problem; not so much this study specfically but the topic. It sounds like there haven’t been that many studies on this topic and it makes me wonder how accurate the science behind this is I also wonder could the results of this test be due to chance. Beside the health issue that may be caused by taking medicine to often; what about the other issues it can cause? I’m not sure if what is in this blog is true, but I have heard that taking medicine every day or very often can make you build up a resistance. This means that the medicine may not help as much or that you may have to take a lot more of it for it to have an affect. This only makes me worry when people say they take medicine all the time. It makes me wonder if perhaps the negavitive affects come from people taking too much of the medicine rather than taking it some times. The article below talk a little more about this issue.

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