How Does Benadryl Raise Blood Pressure?

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Does Benadryl raise blood pressure?

High blood pressure, also called hypertension, is a major risk factor for heart disease. It has several causes including smoking, alcohol, caffeine, obesity, inactivity, emotional stress, heavy metal poisoning, birth control pills, and a diet high in sugar, fat, and salt. But, does Benadryl raise blood pressure?

Doctors define high blood pressure as a systolic reading over 140 mmHg (millimeter of mercury) and a diastolic reading of 90 mmHg and above.

The systole causes the heart to contract, whereas the diastole allows for relaxation between heartbeats. Normal blood pressure is a systolic reading between 120 to 129 mmHg and diastolic of 80 to 85 mmHg.

One in three Americans suffer from high blood pressure or 75 million people. Only half of those actually manage their hypertension properly.

This may be because certain drugs like the antihistamine Benadryl will increase your blood pressure, and this is a problem for those taking antihypertensive drugs.

Nasal congestion is a common symptom in adults with allergies, and Benadryl is, therefore, the go-to treatment. But, does Benadryl raise blood pressure?

This article will explain how Benadryl affects blood pressure, and what natural antihistamines can be used rather than Benadryl.

How Benadryl Works

Benadryl is an allergy medication that includes the antihistamine-active ingredient known as diphenhydramine. It is often used to relieve allergy symptoms, including a runny nose, sneezing, itchy throat, and itchy, watery eyes. In general, Benadryl will come in tablet or cough syrup form.

Let’s explain exactly how Benadryl works.

Histamine is a protein that triggers inflammation throughout the body. When histamine is released during an allergic reaction, it will bind to H-1 receptors along the blood vessels. This increases blood flow and releases other chemicals that contribute to an allergic response, as well as various symptoms and conditions, such as headaches, sneezing, itching, rashes, hay fever, allergies, and nasal congestion.

Antihistamines work by blocking histamine receptors while narrowing the blood vessels. As a result, antihistamines like Benadryl will reduce many of the negative effects associated with histamine.

Antihistamines are also used for hives, eczema, conjunctivitis, and other skin reactions from an insect bite or sting.

Benadryl, Claritin (loratadine), Zyrtec (cetirizine), and Allegra (fexofenadine) are among the brands of antihistamines on the market today.

There are also antihistamines that combine with a decongestant and may be labeled with a “D” ending. The Benadryl allergy plus congestion formula contains diphenhydramine, as well as the nasal decongestant known as phenylephrine.

The decongestant component of this Benadryl formula is designed to temporarily fight sinus pressure and congestion. It is thought to lessen the side effects of antihistamines and further reduce allergy symptoms.

Doctors will often recommend taking antihistamines at night since they can cause drowsiness. Antihistamines can also lead to other side effects, including fatigue, dry mouth, constipation, headaches, blurry vision, confusion, and difficulty with urination. If you experience difficulty speaking, dizziness, shortness of breath, and chest pain, it is best to seek medical attention immediately.

When using antihistamines, it is best not to exceed the recommended dose. Also, alcohol, sedatives, and tranquilizers may increase the drowsiness associated with antihistamines. Side effects may also be heightened when antihistamines are taken alongside certain pain medications, stomach irritation drugs, or antidepressants.

How Does Benadryl Raise Blood Pressure?

Antihistamines like Benadryl may not be effective or safe when you have high blood pressure. So, it is not recommended in those with a hypertension diagnosis. Antihistamines and decongestants, in general, will affect the effectiveness of antihypertensive drugs.

The problem is diphenhydramine and high blood pressure, as taking Benadryl or other antihistamines can cause your heart rate to spike. When the heart works faster and harder, it will add pressure to the arteries. Since there is already too much pressure in the arteries, Benadryl can simply worsen hypertension.

Decongestants and High Blood Pressure

What about phenylephrine and high blood pressure? If you have high blood pressure, you should also avoid antihistamines containing decongestants. In some cases, it can increase blood pressure while also causing unstable heart rhythms, increasing the heart rate over 100 beats each minute.

When the heart rate increases, this causes the blood vessels to narrow, which is also called vasoconstriction. This can lead to various symptoms, such as anxiety, restlessness, headaches, and insomnia.

Sudafed (pseudoephedrine), Vazculep (phenylephrine hydrochloride), and Sudafed PE (phenylephedrine) are common types of nasal decongestants that affect blood pressure.

A meta-analysis of 24 studies and 1,285 patients published in the Archives of Internal Medicine in 2005 found that pseudoephedrine significantly increased systolic blood pressure by 0.99 mmHg and heart rate by 2.83 beats per minute. With that said, there was no effect on diastolic blood pressure, and higher increases were linked with higher doses of pseudoephedrine.

There have also been reports that pseudoephedrine is linked with heart attacks, disturbed heart rhythms, strokes, and other cardiovascular problems.

Studies also show that pseudoephedrine has no significant effect at standard doses on systolic or diastolic blood pressure in controlled hypertensive patients.

Research on phenylephrine’s ability to raise blood pressure is not as extensive as it is with pseudoephedrine. But, some data found that cold medication with phenylephrine showed a clear relationship between high blood pressure and the drug’s administration. Also, blood pressure normalized when the drug was stopped, and no other cause for the hypertension could be explained.

Interestingly, studies that compare phenylephrine with a placebo also show no improvement in nasal congestion—the same thing the drug was intended to treat.

A 2003 Cochrane review also concluded that monotherapy with antihistamines does not significantly alleviate nasal decongestion.

In general, it is crucial to consult your doctor before using Benadryl, including those containing decongestants, especially if you suffer from high blood pressure or heart disease.

Alternatives: Natural Antihistamines

It’s best just to avoid antihistamines and blood pressure problems. If you want to avoid drugs altogether for treating allergies and other allergic conditions like eczema and hives, there are natural antihistamines that can help with this problem.

The following are a few natural antihistamines to consider before taking antihistamines like Benadryl or related medicines containing decongestants.

1. Quercetin

Quercetin is found naturally in onions, citrus fruits, and cruciferous vegetables. Quercetin is a bioflavonoid that stabilizes the release of histamine and controls allergy symptoms.

2. Stinging Nettle 

Research shows that freeze-dried stinging nettle works better than a placebo for allergy relief. The anti-inflammatory abilities of stinging nettle affect key receptors and enzymes in allergic reactions, so it is useful for hay fever, insect bites, and other allergic conditions.

3. Bromelain

Bromelain is found in pineapple and supplements and can treat all sorts of histamine-related conditions like asthma and allergies.

Research also suggests that bromelain can reduce the development of asthma.

4. Neti Pot

The neti pot is a traditional device used in Ayurvedic medicine to clear the nasal passages of allergens and irritants.

Studies show that the neti pot is effective for treating and preventing several upper respiratory infections like the common cold, acute sinusitis, and seasonal allergies.

5. Essential Oils

Some powerful essential oils can also treat allergy symptoms and boost the immune system. Research shows that the anti-inflammatory effects of peppermint oil can help reduce symptoms of bronchial asthma and hay fever.

Other antihistamine essential oils include basil oil, eucalyptus oil, lemon oil, and tea tree oil.

6. Antihistamine Diet

An anti-inflammatory diet will contain natural antihistamine foods. This includes certain fruits and vegetables such as watercress, pea sprouts, garlic, onion, thyme, ginger, turmeric, apples, avocado, coconut oil, pomegranate, capers, peaches, mung bean sprouts, rice, and quinoa.

High blood pressure is a major problem in the U.S. And, among the causes is the use of antihistamines like Benadryl, especially when it contains decongestants.

Taking Benadryl will increase your heart rate, and therefore, the heart must work faster and harder. The added pressure affects the arteries, which worsens in those with hypertension already.

Natural antihistamines are an alternative to Benadryl and can provide some relief. It is beneficial to try an antihistamine diet with lots of vegetables and fruit, quercetin, bromelain, and stinging nettle. The use of a neti pot and essential oils like peppermint oil, eucalyptus oil, or basil oil can also help.


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