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Antihistamine
Prescription antihistamine available online
Learn how prescription antihistamines can help with allergy symptoms and more with a consultation from one of our board-certified doctors online. Get a new prescription for antihistamines or refill an existing prescription today.*
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Non-sedating and sedating antihistamines available*
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About prescription antihistamines
Antihistamines are medications designed to treat allergy symptoms. They’re often prescribed to help treat histamine-mediated conditions, but they’re also used for other conditions. There are two types of prescription antihistamines.
What antihistamines treat
The most common condition treated with antihistamines is allergies. The drugs are designed to bind to H-1 receptors (histamine-1), which play a crucial role in allergic reactions. These prescriptions or over-the-counter products block the effect of histamine. Making antihistamines a valuable treatment option. Predominantly in patients who have an allergic reaction to pollen or other allergies. Such as an allergic reaction to insect stings or bites, conjunctivitis, hives, and hay fever.
Over-the-counter antihistamines can alleviate symptoms like:
Runny nose
Nasal congestion
Itchiness
Nasal swelling
Skin rashes
Watery and itchy eyes
Sneezing
Hives
By managing the symptoms, patients can feel better during the day and get enough shut-eye at night. These medicines that can alleviate allergy symptoms include capsules, pills, and liquids, including eye drops, nasal sprays, and chewable tablets. In medical settings, a healthcare professional can use injectable antihistamines forms. Injectables are often used when there is a severe life-threatening allergic reaction.
Other conditions are also treated with antihistamines, including insomnia and preventing motion sickness. Taking antihistamines can prompt drowsiness by operating against histamine. In some circumstances, these medicines can mitigate sleeplessness when traveling.
Types of antihistamines available online
The 2 types of antihistamine medications are called:
Non-drowsy antihistamine – Medicines like loratadine, acrivastine, fexofenadine, and cetirizine, have fewer odds of making people sleepy.
Drowsy antihistamine – Medicines like cinnarizine, promethazine, diphenhydramine, chlorphenamine (Piriton), and hydroxyzine can make people sleepy.
You can get antihistamines with or without a prescription. OTC products include Allegra, Claritin, Chlor-Trimeton, Tavist, and others. Some are prescription-only medicines with higher concentrations of active ingredients than their OTC counterparts. These can consist of Clarinex, Palgic, Phenergan, and others.
There is no specific antihistamine type that works best for everyone. Some people find specific types to work better for them. The non-drowsy variants seem a popular option when carrying out daily activities. But, if the allergy symptoms stop you from sleeping, then the drowsy medicine can be a more suitable alternative.
H-1 receptor antagonists (blockers)
H-1 receptor antagonists are most often used to treat allergies and allergic rhinitis. Two primary classes of histamine receptors exist. The H-1 receptors and H-2 receptors. The FDA-approved H-1 antihistamines to be used for:
Vomiting
Angioedema
Allergic dermatological reaction
Motion sickness
Non-FDA-approved uses for H-1 medicine are for insomnia. H-1 antihistamines are further classified as first-generation antihistamines and second-generation agents. First generation antihistamines feature Chlor-Trimeton (chlorpheniramine) and Benadryl (diphenhydramine).
First-generation antihistamines can manage your sleep-wake cycle, all thanks to their sedative compounds. Sedating antihistamines have an easier time crossing the blood-brain barrier, while second-generation antihistamines don’t.
Second-generation antihistamines lack such sedative compounds. Classic examples of second-generation products include Loratadine (Claritin) and Fexofenadine (Allegra).
Some allergy medications work differently in the system and could be safely used together. For example, if you take an oral antihistamine like cetirizine, you can also use ketotifen or antihistamine eye drops to treat symptoms of watery eyes or itchy eyes.
Nasal sprays, decongestants, and steroids could be taken alongside oral antihistamines. They can work differently to relieve symptoms like congestion or runny nose. But, it is crucial to talk to a healthcare provider before using any medications together to alleviate the symptoms.H-2 receptor antagonists (blockers)
Antihistamines that bind to H-2 receptors are often used to treat upper gastrointestinal problems. These problems are triggered by too much stomach acid. H-2 antihistamines can treat the symptoms of:
Peptic ulcer
Zollinger Ellison syndrome
The non-FDA-approved uses are for indigestion. The most commonly used H-2 antihistamine is Famotidine. Other examples of H-2 receptor antagonists include Cimetidine and Nizatidine.
When you choose which medication to take, please consult a specialist. For minor health problems, you can go for OTC products. See if the product you are interested in matches the symptoms you want to treat. Prescription-only antihistamines are stronger than OTC products and are better at alleviating severe allergies.
How antihistamines work
Antihistamines function by blocking or reducing histamine. Thus, stopping the symptoms of an allergy. When the body comes in contact with an allergy trigger, it stimulates the production of a substance called histamine. That trigger can be anything, from dust mites and pollen to pet dander and ragweed.
The tissue in the nose begins to swell, which ends up causing a running or blocked nose. And watery eyes. At other times, people get hives or other skin rashes, which cause itchy skin. Antihistamines are here to stop the reaction to indoor, food, and seasonal allergies.
A healthcare provider might suggest using a decongestant with an antihistamine for a blocked nose. Nasal sprays work to ease the sneezing, runny, or itchy nose, including a postnasal drip. The doctor can suggest eye drops if you are dealing with eye allergies. These drops work to ease the swollen, red, and itchy eyes.
You need to know how to store the allergy meds to make sure they work. Each medication has unique storage requirements, such as keeping them at room temperature or in the fridge. Check the exact storage instructions on the product you are using. You'll need to store the medicine in a dry area, preferably the bedroom. Avoid putting them in the kitchen or bathroom. Moisture and heat can damage the medicine.
Keep the product away from the reach of pets and children. If you notice the antihistamines have expired, throw them away. Don’t use the medicine beyond its expiration date. Keep the original packaging or container of the product. These are designed to provide the medication with optimal storage. If you plan to travel, carry the medicine into the cabin. The cabin maintains stable moisture and temperature levels, which can work well for your medication.
Most syrups and liquids require storage of about 15°C to 30°C. This means you wouldn’t be storing it in the fridge. Check the packaging on the bottle to find optimal storage. Keep the product closed when not in use to prevent a contamination risk with eye drops. Store it away from direct sunlight. Light and heat can also damage sprays.
Side effects of antihistamines
When taken as prescribed, antihistamines are generally well tolerated. However, they can still cause some side effects.
The more common side effects of antihistamines include:Confusion
Blurry vision
Dry mouth
Drowsiness
Vomiting
Nausea
Dizziness
Moody behavior
Trouble urinating
In rare cases, antihistamines may cause serious side effects. These can include:Delirium
Euphoria
Reduced coordination
According to peer-reviewed studies, H-1 antihistamines typically cause more noticeable side effects. These side effects are more common with first-generation antihistamines. Second-generation antihistamines have limited side effects.
A dry mouth is one of the most well-recorded side effects. Some patients also experience tinnitus and dizziness. With increased dosages, poor coordination and euphoria can happen. Delirium is a probable side effect at much higher doses.
H-2 receptors tend to be well-tolerated. But, they can still cause side effects. Gastrointestinal changes, confusion, dizziness, and fatigue can occur. One particular drug in this category that could trigger various side effects is cimetidine. It can lead to enlarged breast tissue in men (gynecomastia) and milky nipple discharge (galactorrhea) in women.Antihistamine risks
Antihistamines are generally safe, but there are some risks if you have other medical conditions or take certain medications.
Before you take a prescribed antihistamine, be sure to tell your doctor if you have any of the following health conditions or issues:Glaucoma
Liver disease
Kidney disease
Difficulty urinating due to prostate enlargement
Breathing difficulties (i.e., chronic bronchitis, emphysema, or asthma)
H-1 anthistimatmines are powerful muscarinic receptor antagonists. They can cause severe anticholinergic side effects such as dry skin, constipation, urinary retention, etc. Urinary retention can be especially problematic for men with BPH. In women, it could amplify the risk of urinary tract infections. Second-generation products are often seen as a safer variant for older adults who need to treat their allergies and allergic rhinitis.
To minimize the risk of side effects or other health problems, take only the recommended amount, specified on the label. If you take more, it won’t work faster or better. Instead, it can be dangerous for your health. If you have an Allegra allergy or Zyrtec allergy, talk to a doctor to get other medicines that can accommodate your needs.Antihistamine drug interactions
When you begin a new medication, make sure to tell your doctor about any other medications, supplements, or herbs you’re taking. Some medications that might interact with an antihistamine include:
Other antihistamines (i.e., ointment, diphenhydramine cream, and spray)
Blood pressure medication (such as beta blockers and calcium channel blockers)
MAO inhibitors
Seizure meds
Narcotic pain medicine
Muscle relaxants
Talk to a pharmacist or healthcare expert if you use other products that can lead to drowsiness, like cough relievers, pain meds, and drugs for anxiety and sleep. Using cannabis and alcohol can also make you drowsy, so avoiding products that can lead to a drop in blood pressure and drowsiness is essential.
If you plan on using products like these, consult an expert about using them safely. Antihistamines could interfere with some lab/medical tests, such as urine drug testing and brain scans for Parkinson’s disease. Therefore, it would be best to notify the lab personnel if you are using antihistamines.
Antihistamines you can get online
Antihistamines FAQs
How should I take antihistamines?
The doses will vary from patient to patient. Stick to your doctor’s instructions or follow the label. When taking the medicine by mouth, you can take it with a glass of water, milk, or food. This can help minimize stomach irritation. If you are using an extended-release tablet, then you need to swallow it whole. Avoid crushing, chewing, or breaking the product.
Who shouldn’t take antihistamines?
You shouldn’t be using antihistamines if you are also using specific other prescription drugs such as erythromycin, which is an antibiotic or drugs for alleviating fungal infections.
When your doctor suggests you use antihistamines, be sure to let them know of any other medicines you might be using, including other health conditions, you might have such as high blood pressure, thyroid, heart disease, glaucoma, or BPH.How long does it take for antihistamines to work?
Most of the time, the effects of a table start to kick in in about half an hour. They reach their peak in efficiency in roughly 2 hours. Whether you are using nasal sprays, eye drops, injectables, liquids, or chewable tablets, their efficiency will vary. You will know if the product is working when the symptoms of your allergy start to subside or are completely relieved.
What should I avoid with antihistamines?
Some medicines don’t mix well with antihistamines. Drugs that could trigger problems with this type of treatment are antidepressants, indigestion, or stomach ulcer medicines, as well as cold and cough remedies that also feature an antihistamine.
When treating an allergy with a product like this, avoid drinking alcohol. Alcohol can increase the odds of drowsiness and make you sleepy. Other consumables, foods, and drinks don’t affect most antihistamines. However, be sure to check the leaflet for other things you should avoid.What do antihistamines do to your body?
When you are allergic to something, the immune system goes into an overload. All in an effort to protect the body from infection. The immune system reacts to something that is not supposed to be harmful, like pollen. So, the immune system ends up releasing too much histamine. This is the reason behind the throat, nose, sinuses, lung inflammation, and other reactions. Antihistamines block the effects of histamine. Therefore, curbing its impact.
Which drugs are antihistamines?
These drugs are divided into two primary types: non-sedating and sedating antihistamines. Sedating anthisitamines can make you feel sleepy since they move with ease from the blood to the brain. For example, chlorphenamine maleate and promethazine hydrochloride. These are often first-generation antihistamines. Non-sedating are the newer variants that have lower odds of making you feel sleepy, such as acrivastine and loratadine.
What is antihistamine used for?
Antihistamines are drugs you use to stop the symptoms of allergies. They are mainly used for symptoms like itching, skin rash, sneezing, hives, allergic asthma, allergic conjunctivitis, insect bites, and stings. Some patients might also use them for travel sickness.
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Antihistamines pricing details
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Antihistamines resources
Sources:
PlushCare is dedicated to providing you with accurate and trustworthy health information.
Cleveland Clinic: "Antihistamines." Cleveland Clinic. Accessed on December 14, 2023, at https://my.clevelandclinic.org/health/drugs/21223-antihistamines.
MedlinePlus: "Antihistamines." MedlinePlus. Accessed on December 14, 2023, at https://medlineplus.gov/ency/patientinstructions/000549.htm.
Mayo Clinic: "Antihistamine (Oral Route, Parenteral Route, Rectal Route)." Mayo Clinic. Accessed on December 14, 2023, at https://www.mayoclinic.org/drugs-supplements/antihistamine-oral-route-parenteral-route-rectal-route/description/drg-20070373.
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