Antihistamines are a class of medication the treat allergy symptoms, such as sneezing, runny nose, and also itching. As with any kind of medication, taking too much deserve to be harmful.

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Some antihistamines likewise work as sleep aids, cold and flu medicine, and motion sickness treatment.

People should follow the dosage indict on the packaging or your doctor’s advice to prevent an overdose. Lock should likewise keep antihistamines, and all medications, out of with of children.

If a human takes too lot antihistamine, they might experience adverse and also sometimes serious effects. Constantly call a physician or a poison control facility if an antihistamine overdose occurs.

Share top top PinterestA person who overdoses ~ above antihistamines might experience fever, dilated pupils, and a fast heart rate.
People have the right to overdose ~ above any form of antihistamine. Antihistamines space a drug, and there is a safe limit to just how much a person deserve to take in ~ one time.

This limit relies on several factors, including:

the age and also size that the personthe form of antihistamine lock took and also how muchany health problems they have actually other medication the person takes

If a healthy adult takes just a slightly higher dose the antihistamine, such as accidentally taking two pills instead of one, your symptoms may not it is in serious, or they might not have any kind of symptoms.

However, a bigger overdose, specifically in children or larger adults, may cause serious symptoms. Toxic doses that antihistamines may occur when a human being takes 3 to 5 time the typical amount.

No matter how much a human overdoses, they should seek medical help or speak to a poison regulate center.


A position statement indigenous the Canadian society of Allergy and also Clinical Immunology (CSACI) says that first generation antihistamines can have “intolerable and also potentially life threatening adverse effects.”

Research mirrors that an initial generation antihistamines deserve to have results on the main nervous device in big doses.

Examples of an initial generation antihistamines include:

diphenhydramine (Benadryl)chlorpheniraminebrompheniramine

These antihistamines may reason jitteriness or drowsiness.

Second generation antihistamines carry out not usually have these effects. Second-generation antihistamines are generally used medications, including:

loratadine (Claritin)cetirizine (Zyrtec),fexofenadine (Allegra)

Signs and also symptoms that antihistamine overdose in children may include:

being very excited or jitteryirritabilityhallucinationsseizures

After these symptoms appear, a child may experience:

drowsinessslowed breathing

Symptoms that antihistamine overdose in adults may include:

flushingdilated pupilscomaan inability to empty the bladder completely (urinary retention)

Second generation antihistamines tend to be much less serious v an overdose.However, any type of overdose deserve to be dangerous, and people have to seek help from a medical professional or poison control immediately.

Some antihistamines room safe for youngsters to take. However, the Food and also Drug management (FDA) caution the just because a product states it is for kids does not typical a boy of any type of age deserve to take it.

Research on antihistamines states that children and older adults are more at risk of an antihistamine overdose 보다 adults.

One study uncovered that kids have experienced heart problems, seizures, and even fatality from an antihistamine overdose. The most typical reactions space mild, however, and also include:


Second generation antihistamines are much less likely to reason toxicity in kids than first generation ones, follow to a study of much more than 9,000 children.

However, an additional study foundthat second generation antihistamines can cause dangerous symptoms when youngsters overdose top top them.

Diagnosing an antihistamine overdose commonly starts through a discussion around all drugs the human is taking and also not simply the antihistamines. This is because some various other medications, such as cold, flu, and also sleep medications, save on computer antihistamines.

If a human takes among these other medicines and also takes an allergy medication, they may accidentally overdose.

Other medications, such as certain antidepressants and motion sickness drugs, can also cause an overdose if a human being mixes them with antihistamines.

If someone is not sure around the lot of antihistamine they took, a doctor may need to command a physical exam. They may look for signs such together drowsiness, irritability, blurred vision, or seizures. Castle may likewise check the love rate, breath rate, and blood pressure.

In part cases, a human may require blood test or further observation in a hospital.

In soft cases, an separation, personal, instance may be able to use self-care at home. However, castle should always call the AAPCC or a medical professional to be sure this is safe.

If the human is experiencing major symptoms, they might need hospitalization, consisting of heart monitoring, intravenous (IV) fluids, and medication.

In part cases, physicians may offer a human being activated charcoal, which helps avoid the absorption of some medications and chemicals in the gut. They may likewise use ipecac syrup, which reasons the human being to vomit. This can cause any type of excess medicine to leaving the body in the vomitus.

Antihistamines may be first generation (sedating) or 2nd generation (nonsedating). These two varieties may lead to various reactions if a human being takes as well much.

First generation antihistamines are an ext likely to cross the blood-brain barrier. This way they can make human being dizzy or drowsy, even in normal doses.

Second generation antihistamines are more recent drugs and are much less likely to have these effects. Nonetheless, people can overdose on both types.

First generation antihistamines available over-the-counter include:

diphenhydramine (Benadryl) chlorpheniramine (Chlor-Trimeton)brompheniramine (Dimetapp)clemastine (Tavist)doxylamine (Unisom)hydroxyzine (Vistaril)promethazine (Promethegan)triprolidine (Actidil)

These medications can act together sedatives, so they can make a person feel exhausted or dizzy.

Some professionals say first generation antihistamines are much more likely to an outcome in fatality from accidents or overdoses than their 2nd generation counterparts.

Second and third generation antihistamines easily accessible over the respond to include:

cetirizine (Zyrtec)fexofenadine (Allegra)loratadine (Claritin)

These newer antihistamines are less likely to reason drowsiness and dizziness. Research has discovered them much less likely to reason dangerous results if a person takes also much.

Antihistamines are frequently safe once a person takes the exactly amount. However, as with any type of medication, castle can reason serious adverse effects if who takes too much.

People need to keep antihistamines and also all medications out of reach of children. Part antihistamines room safe for youngsters to take, however it is essential to questioning a medical professional or pharmacist about the right dose.

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Different antihistamines have different dosages. That is crucial to check out labels carefully to be sure a human being is not taking as well much.

If an overdose happens, seek immediate medical attention or contact the AAPCC at 800-222-1222.