Antihistamine drugs are used to treat allergic reactions. They prevent or lessen symptoms such as itching, sneezing, watery eyes and runny nose. Antihistamines may help relieve allergy symptoms when taken with other medications. These drugs include diphenhydramine (Benadryl), chlorpheniramine (Chlor-Trimeton) and sulfa drugs like albuterol (beta blockers). Antihistamines are available over the counter and prescription only. You will need to get your doctor’s OK before taking any medication containing these drugs.
What Are Antihistamines Used For?
Antihistamines are prescribed for allergies, but they may also be helpful in treating colds, flu symptoms and other conditions. Some antihistamine drugs have been shown to reduce swelling caused by certain types of cancer chemotherapy, including some forms of bone marrow transplantation. Antihistamines may also help with migraine headaches.
Antihistamines are usually given as a pill or liquid form. Most contain one or two active ingredients called histamine antagonists.
Histamine is a chemical that causes allergic reactions in the body. When it comes into contact with something that triggers an allergic reaction, it releases chemicals that cause inflammation and pain. These medications block the release of histamine from mast cells in the nasal passages so they don’t trigger an allergic response anymore.
Common examples are:
Antihistamines have many brand names. Their active ingredient is the same, but some may work faster or last longer than others.
They are available over the counter (OTC) and by prescription. Antihistamines can cause drowsiness, dry mouth and other side effects.
They seem to help relieve a runny nose, itchy eyes and sneezing caused by hay fever, ragweed and other types of allergies.
They can also relieve hives and itching caused by insect bites and some drugs.
Antihistamines can help relieve the following conditions:
Antihistamines are available as tablets, capsules, liquids, creams or nose sprays and are usually taken by mouth. They are often used to treat skin conditions like hives and eczema.
They can also be applied to the skin to relieve itching, burning and swelling caused by insect bites. Antihistamines are available without a prescription in lower strength formulations.
Antihistamines should be taken only if recommended by a health care provider. If you have an allergic reaction to one, your provider may have already determined which antihistamine would be best for you.
Follow the directions on the package or prescription label. Take the antihistamine with food if it causes an upset stomach. If you are using a spray, shake the bottle well before each use.
Take this medication exactly as prescribed. Do not take larger amounts or take it for longer than recommended by your health care provider.
Your condition will not improve any faster and this may cause a serious rise in your blood pressure. Antihistamines work best if you take them when you first experience symptoms.
Continue to take the medication for as long as your doctor prescribes it, even if you feel better. Do not stop taking it without consulting your doctor.
Drugs such as antihistamines may cause drowsiness. Do not drive or operate heavy machinery until you know how the drug affects you.
The antihistamines in this medication class often cause dryness of the mouth. This side effect may be lessened if you drink plenty of water.
Other side effects may also occur. If you experience severe dizziness or drowsiness, rapid heartbeat, shortness of breath or any other troubling symptoms, contact your health care provider immediately.
Older adults may be more sensitive to the effects of this drug, especially drowsiness and problems with coordination.
Other drugs may interact with antihistamines. Tell your health care provider about all the prescription and over-the-counter medications you use.
This includes vitamins, minerals, herbal products and drugs prescribed for others, such as cough and cold medicines. Do not start using a new medication without telling your provider.
Go to the emergency room if your face swells, you have difficulty breathing, or your mouth fills with foam. These can be signs of a serious allergic reaction.
Before taking this medication, discuss with your doctor if you are pregnant, plan to become pregnant or are breastfeeding. Do not take this medication without first discussing it with your doctor.
The active ingredient in Histadelics is Azelastine Hydrochloride and it is an anti-allergy medicine that works by blocking the action of histamine, which reduces the symptoms of an allergic reaction such as inflammation and watery eyes.
Since anti-allergy medicine helps your body fight off infection, it can also be used to help prevent allergy symptoms before they start. Taking it regularly at the first sign of spring can prevent hay fever symptoms from developing.
It is an over-the-counter drug that does not require a prescription.
You can buy the anti-allergy tablets from drugstores or supermarkets. They are available in a range of brands, pack sizes and prices.
You can also buy them online via the Internet, either directly from the pharmacist or from an online pharmacy. It’s important to buy only from trusted websites; if possible, one with a license issued by your national regulatory body.
Sources & references used in this article:
An evidence-based review of the efficacy of antihistamines in relieving pruritus in atopic dermatitis by PA Klein, RAF Clark – Archives of dermatology, 1999 – jamanetwork.com
The efficacy of short-term administration of 3 antihistamines vs placebo under natural exposure to Japanese cedar pollen by S Hyo, S Fujieda, R Kawada, S Kitazawa… – Annals of Allergy …, 2005 – Elsevier
Advances in H1-Antihistamines by FER Simons – New England Journal of Medicine, 2004 – Mass Medical Soc