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How Does Histamine Affect Asthma

Youll Enjoy The Great Outdoors More

Allergy Cure That Worked – Part1: Histamines

Many people experience worse allergy symptoms when theyre outside. If you love spending time outdoors, it can be hard to decide whether you want to go hiking while drowsy or suffering from allergy symptoms.

Luckily, you can enjoy nature to the fullest when you cure your allergies. All of a sudden, youll find outdoor activities, like backpacking, camping, barbecues, and gardening much more enjoyable.

What Is An Antihistamine

An antihistamine is a drug that targets and inhibits the physiological response our body has to histamines. These drugs are common, frequently used to control allergies, but come in different forms.

A diphenhydramine, like Benadryl, is highly effective but anyone who has taken one knows that you wont function well after, due to its sleepy side effects. Not all antihistamines will put you to sleep though. Other common antihistamines are: chlorpheniramine and loratadine. Each target the same goal, to control the inflammatory response to histamines, through different physiological pathways, so each has a slightly different effect.

Role Of Histamine In Allergic Disease

Histamine plays a central role in the pathogenesis of several allergic diseases, such as atopic dermatitis, allergic rhinitis, and allergic asthma through differential regulation of T helper lymphocytes. Enhancement of Th2 cytokine secretion and inhibition of Th1 cytokine production are mediated by histamine. Thereby, histamine regulates the effective balance between Th1 and Th2 cells by assisting a shift toward Th2 . Histamine-mediated mast cell activation plays a critical role in various allergic diseases. Histamine may induce the release of leukotrienes, cytokines, and chemokines via H4R in CD34+ cord blood-derived human mast cells . In mouse mast cells, both histamine and 4-methylhistamine can induce IL-6 production individually, an effect that is potentiated by LPS stimulation. This effect can be blocked by H4R antagonists and does not occur in H4R-deficient allergic mice . Recent findings have shown that activation of H4 receptors by histamine stimulates the synthesis of IL-4 and IL-5 in human cord blood mast cells and tumor necrosis factor in bone marrow-derived murine mast cells , both of which have a potential role in inducing allergic inflammation .

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Do Antihistamines Cause Dementia

Long term use of some antihistamines may increase your risk of dementia. Diphenhydramine blocks the effects of a neurotransmitter called acetylcholine. This neurotransmitter is vital for memory and learning. Diphenhydramine increased the risk of dementia by 54% in one 3,000 patient study followed for seven years.

How Histamine Intolerance Affects Your Brain

Doxophylline and asthma

By now youre likely aware of the effects of histamine on your overall health and how an excess of histamine is the reason behind your chronically dripping nose, digestive issues like bloating and cramps, and other irritating allergic reactions like a rash, itchy eyes and a scratchy throat. You already know that histamine forms as part of many essential processes related to your immune response, and why the foods you eat trigger histamine, but did you know that histamine plays a crucial role in your brain, too?Surprisingly, the histamine response in your brain that can have such a profound effect on your mood, ability to concentrate, and overall brain function. Today, you’re going to discover the link that living with high histamine has with your sleep troubles, emotional imbalances and stress responses.

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Products Contraindicated With Asthma

Asthma was once a labeled contraindication for allnonprescription products containing first-generation antihistamines. Therationale behind this labeled contraindication was discussed by an OTCreview panel appointed to examine antihistamines in its original 1976report: The Panel is aware that a controversy exists concerning the useof antihistamines in patients with bronchial asthma where a dryingaction is undesirable. Many physicians consider this effect to bedisadvantageous in patients with bronchial asthma and some maintain thatthe antihistaminic drugs are contraindicated in patients with thisdisease.2 Products carried this label for years. In 1985,the FDA published a tentative final monograph for antihistamines,agreeing with the need for this label.3

In 1992, however, the FDA published its final rule on labeling for nonprescription first-generation antihistamines.4In this document, the agency described the conclusions of a 1990meeting of the FDAs Pulmonary-Allergy Drugs Advisory Committee.Participants believed that first-generation antihistamines did not havesufficient anticholinergic effects to be problematic for those withasthma, removing the term asthma from the warnings. Second-generationantihistamines have never beenrequired to carry an asthma warning.

What Happens When Youre Dehydrated

So, most of us with allergies know about histamine.1-4 We know of it as a mediator of inflammation. Its stored in mast cells lining most tissues inside our bodies. Its used by the immune system to cause inflammation. This inflammation helps trap and kill pathogens. Its also involved in both the allergy and asthma responses.1

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Dehydration Can Worsen Exercise

Hydrating is especially important for those with asthma caused by exercise. When you exercise you tend to breathe through your mouth, causing dry air to enter your lungs. This dry air can contain triggers such as pollen or pollution, causing asthma symptoms. Keep your airways hydrated by drinking plenty of water each day and breathing your nose, which helps moisten and filter the air before it gets into your lungs.

Cold Air Dries The Airways

Allergies, Asthma and Dehydration

When you breathe in cold, dry air, the thin layer of fluid that lines your airways evaporates faster than it can be replaced. This leads to irritated and swollen airways, and a worsening in asthma symptoms. In addition, cold air encourages the production of histamine, which plays a role in immune response and inflammation.

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What Should Health Care Professionals Do

Health care professionals should consider the risks and benefits of montelukast when deciding to prescribe or continue patients on the medicine. Counsel all patients receiving montelukast about mental health side effects, and advise them to stop the medicine and contact a health care professional immediately if they develop any symptoms included but not limited to those listed in the table above. Be aware that some patients have reported neuropsychiatric events after discontinuation of montelukast.

Only prescribe montelukast for allergic rhinitis in patients who have an inadequate response or intolerance to alternative therapies.

Histamine Receptors And Their Role In Allergic Inflammation

Histamine receptors are characterized by their function, structure, distribution, and their affinity to histamine . Histamine has diverse effects, both pro-inflammatory and anti-inflammatory, which are determined by both the histamine receptor subtype and the cells stimulated types . The H1-receptor drives cellular migration, nociception, vasodilatation, and bronchoconstriction , whereas the H2-receptor modifies gastric acid secretion, airway mucus production, and vascular permeability . The H3-receptor plays an important role in neuro-inflammatory diseases . The H4-receptor has also been shown to be involved in allergy and inflammation . H4R-mediated mast cell activation can regulate a powerful inflammatory cascade by releasing several inflammatory mediators these mediators may stimulate the migration of different inflammatory cells into the inflammatory site . Likewise, the activation of H1R also regulates allergic responses by enhancing the migration of Th2 cells toward the allergen during lung inflammation . A more detailed summary of histamine receptor expression is shown in Table 1.

Table 1. Expression of different histamine receptors on various cells.

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A New Insight On The Immunological Pathway In Asthma

Asthma is an inflammatory disorder of the conducting airways that has a strong association with allergic sensitization. The disease is characterized by a polarized Th-2 -type T-cell response and the levels of IL-4, IL-5, and IL-13 are upregulated in the airways of patients with bronchial asthma . After an exposure to allergens, specific IgE on the high-affinity IgE receptors of mast cells conjugates with allergens, IgE and allergen complex activate mast cells through IgE receptors and release chemical mediators including histamine, leukotrienes, prostaglandins, and so forth. This immunological event causes an immediate reaction in the airways of asthmatics.

However, over the past decade, the understanding of asthma pathogenesis has made a significant shift from a Th2 cell-dependent, IgE-mediated disease to a more complicated heterogeneous disease. Recent studies clearly show that not only Th2 cytokines but also other T-cell-related cytokines such as IL-17A and IL-22 as well as epithelial cell cytokines such as IL-25, IL-33, and thymic stromal lymphopoietin are involved in the pathogenesis of asthma. Recently, type 2 innate lymphoid cells were found to represent a critical innate source of type 2 cytokines . In the classical immunological pathway, the role of mast cells is critical in the immediate reaction.

Will Aspirin And Other Pain Relievers Make My Asthma Worse

Histamine Intolerance: Causes, Symptoms, and Diagnosis in ...

Aspirin and other drugs called nonsteroidal anti-inflammatory drugs may be harmful for people who have asthma. Ibuprofen and naproxen are a few examples of NSAIDs. If you are allergic to aspirin, ask your doctor or pharmacist to make sure any new medicine you might take is not related to aspirin.

People who have asthma can usually take acetaminophen safely. This medicine is typically used to relieve fever and pain. Very rarely, even acetaminophen may make asthma worse, which has prompted further studies to explore the link between acetaminophen and asthma. If acetaminophen makes your asthma worse, tell your doctor. He or she can help you find another type of pain reliever.

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How Do Antihistamines Stop The Symptoms Of Allergies

If you have ever had seasonal allergies, you have probably taken antihistamines to feel better. Five out of every ten people deal with allergies of some kind. Allergens are the triggers for an allergic response. Allergens can be anything from the latex in gloves, to pollen, dust mites, animal dander, mold, insect stings, as well as ingredients in medications and in food.

The allergic response is caused by the protein, histamine the immune system makes and carries histamine in special lymphocytes called mast cells. Histamine is an inflammatory protein that causes blood to flow into the surrounding tissues of where the antigen is located. For instance, if you breathed in some dust particles and the immune system mistakes them for a pathogen, the tissues in your sinuses and nasal passages may begin to swell. You may start sneezing and your eyes might start watering this is caused by histamine.

To help reduce your allergy triggers, you need to reduce the amount of allergens that you are exposed to. A good way to do this is to keep your environment free of dust, dust mites, and mold. The spores of mold are airborne it is possible that you could breathe them into your lungs and have an allergic response. Dust mites live in the dust of your home they also live in your bed and bedding. A dust mite allergy can cause coughing, wheezing and sinus problems.

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Histamine In The Pathophysiology Of Asthma

Curry reported a historical finding concerning asthma pathophysiology, showing histamine induced bronchoconstriction in asthmatics by injection or inhalation at a low dose of histamine that had no effect in normal subjects . Based on these results, the concept of airway hyperresponsiveness to histamine as a physical characteristic of asthmatics was proposed. Afterward, since the airways of asthmatics were hyperresponsive to many airway smooth-muscle-contracting agents, it has been recognized as nonspecific airway hyperresponsiveness showing airway abnormality .

Terfenadine, a strong H1RA, induced bronchodilation in asthmatics the same as 2-stimulant. This result suggested that the continuous release of histamine from mast cells in the lung of asthmatics was causing contractive tension of the airway smooth muscle. These lines of evidence suggested that histamine was deeply involved in the asthma pathophysiology. Furthermore, terfenadine reversed completely the decrease in the forced expiratory volume in one second as an index of airway obstruction induced by histamine. On the other hand, terfenadine reversed partially the decrease of FEV1 induced by allergen inhalation .

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The Rise In Food Allergy Cases

The number of people with food allergies has risen sharply over the past few decades and, although the reason is unclear, other allergic conditions such as atopic dermatitis have also increased.

One theory behind the rise is that a typical child’s diet has changed considerably over the last 30 to 40 years.

Another theory is that children are increasingly growing up in “germ-free” environments. This means their immune systems may not receive sufficient early exposure to the germs needed to develop properly. This is known as the hygiene hypothesis.

Key Steps To Reduce The Likelihood Of An Attack:


Take your asthma medication

If you are asthmatic and have a pollen allergy, ensure you have your asthma medication with you at all times. Particularly your blue reliever inhaler.

But also take your hay fever medicine

Research has shown that asthma sufferers who also have hay fever can significantly reduce their risk of needing to go to A& E if they treat their hay fever effectively.

Antihistamines will reduce your sensitivity to the histamine released by your body in response to the pollen.

If you are taking Fexofenadine ensure you are not taking them with orange juice or grapefruit as this can dramatically reduce the efficacy of your medication.

Read our full article on how grapefruit affects your medication

Some antihistamine medications become less effective after continued use. If one antihistamine is not working for you, speak with your pharmacist and try alternatives to see if others work better.

Be careful taking antihistamines that can cause drowsiness.

Many of the same antihistamine medication is marketed by different drug companies, look carefully at the generic name of the medication and you may find it is possible to buy the identical medication much cheaper as a generic brand. Ask your pharmacist to help and advise.

When does hay fever season start?

Grass pollens are the most common cause of hay fever, being the trigger for 95% of peoples hay fever. It usually affects people in May, June and July.

Also Check: What Molecules Are Affected By Asthma

Histamine Transport In The Pathophysiology Of Asthma

Histamine is synthesized and stored in the vesicles of mast cells and basophils . Upon immunological stimulation of mast cells and basophils, histamine is released from storage vesicles into the extracellular space activating G-protein-coupled receptors H1, H2, H3, and H4 . However, to terminate the effects of histamine via histamine receptors on targets cells such as bronchial smooth muscle cells, the histamine concentration in the extracellular space should be regulated by the degradation of histamine.

The degradation enzyme, HMT, is critical in metabolizing histamine into inactive forms of the metabolite and was documented to be significant for the relationship between airway responsiveness and HMT activities when using the HMT inhibitor, , in animal models . Biochemical analysis suggested that the HMT enzyme is primarily localized in cytoplasmic space , while histamine is unable to easily enter the intracellular space because at physiological pH, histamine exists as an organic cation. Therefore, transport machineries of histamine are required to enter the intracellular space and to obtain access to the HMT enzyme.

How Do You Know If Food Is One Of Your Asthma Triggers

If you think certain foods trigger your asthma symptoms or your childs symptoms, talk to your GP or asthma nurse as soon as possible. This is important because an asthma attack triggered by an allergic reaction to food can be worse, particularly for children.

Your GP or asthma nurse can help you work out if youre allergic or sensitive to certain foods. They can:

  • refer you for an allergy test to confirm or rule out any food allergies, usually a skin prick test
  • help you identify foods youre sensitive to that dont show up in allergy tests by supporting you to keep a food and symptom diary, which you can review at your appointment
  • support you in excluding certain foods or food groups for a while, and reintroducing them safely to see which foods trigger asthma symptoms
  • confirm or rule out anything else which could be making your asthma worse, such as acid reflux
  • update your asthma action plan with new food triggers, and any action you need to take if your asthma symptoms are triggered by food.

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What Questions Should I Ask My Healthcare Provider

  • What type of antihistamine would work best for me?
  • How do I proper take the prescribed antihistamine?
  • What side effects might occur with the recommended medication?
  • What antihistamine wont interfere with the current medications I am taking?
  • When, or for what conditions, does taking an antihistamine that would make me drowsy make sense?
  • Can I live my life normally while using this medication? Can I drive? Can I operate heavy machinery?
  • Can I take antihistamines if I am pregnant, planning to become pregnancy or am breastfeeding?
  • Can antihistamines be safely given to my child?
  • What are the consequences if I dont take an antihistamine to help with my allergies?

A note from Cleveland Clinic

Histamine is on your side. The chemical does its best to regulate help your heart and lungs and protect your body from foreign allergens, among other roles. But it can be oversensitive, and it can overreact, and thats where antihistamines can help. If youre have allergies, stomach symptoms or any of the other conditions and symptoms mentioned in this article, talk to your healthcare provider about your options. Your symptoms may be able to be treated.

Always check with your healthcare provider and your pharmacist if you have concerns about antihistamines, and always follow the directions on the labels!

Common Side Effects Of Allegra Vs Claritin

Do you have more than just Histamine Intolerance? Take the ...

Allegra and Claritin share some mild side effects such as headache, drowsiness, and fatigue. These side effects are common with other second-generation antihistamines like Zyrtec . However, Allegra may produce less drowsiness than Claritin and other antihistamines.

Other common side effects of Allegra include dizziness, nausea, stomach ache, and back pain. Claritin may also cause dry mouth.

Serious side effects are rare with Allegra and Claritin. However, allergic reactions to any of the ingredients in either drug are possible. Those with allergies to either drug may experience rash, swelling, or trouble breathing. Seek medical attention immediately if this occurs.

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