Antihistamines room a class of medication that treat allergy symptoms, such together sneezing, runny nose, and also itching. Together with any kind of medication, taking too much have the right to be harmful.

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Some antihistamines also work together sleep aids, cold and also flu medicine, and motion sickness treatment.

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

If a person takes too lot antihistamine, they may experience adverse and sometimes serious effects. Constantly call a medical professional or a toxicity control center if an antihistamine overdose occurs.

Share top top PinterestA human being who overdoses ~ above antihistamines might experience fever, dilated pupils, and also a fast heart rate.
People can overdose top top any type of antihistamine. Antihistamines are a drug, and also there is a for sure limit to just how much a person can take at one time.

This limit relies on several factors, including:

the age and size that the personthe type of antihistamine castle took and also how muchany health conditions they have actually other medicine the person takes

If a healthy adult takes only a slightly greater dose of antihistamine, such together accidentally taking 2 pills rather of one, their symptoms might not be serious, or they may not have any kind of symptoms.

However, a larger overdose, especially in children or older adults, may reason serious symptoms. Toxic doses that antihistamines may happen when a human being takes 3 come 5 times the normal amount.

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


A place statement native the Canadian society of Allergy and also Clinical Immunology (CSACI) says that first generation antihistamines deserve to have “intolerable and potentially life threatening disadvantage effects.”

Research reflects that an initial generation antihistamines have the right to have impacts on the central nervous device in large doses.

Examples of very first generation antihistamines include:

diphenhydramine (Benadryl)chlorpheniraminebrompheniramine

These antihistamines may reason jitteriness or drowsiness.

Second generation antihistamines execute not usually have actually 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 an extremely excited or jitteryirritabilityhallucinationsseizures

After this symptoms appear, a child may experience:

drowsinessslowed breathing

Symptoms of antihistamine overdose in adults may include:

flushingdilated pupilscomaan inability to north the bladder totally (urinary retention)

Second generation antihistamines tend to be less serious with an overdose.However, any overdose have the right to be dangerous, and people should seek help from a medical professional or poison regulate immediately.

Some antihistamines space safe for kids to take. However, the Food and also Drug management (FDA) caution that just because a product says it is for youngsters does not average a child of any type of age have the right to take it.

Research ~ above antihistamines says that children and also older adult are an ext at threat of one antihistamine overdose than adults.

One study discovered that youngsters have skilled heart problems, seizures, and also even fatality from one antihistamine overdose. The most typical reactions space mild, however, and include:


Second generation antihistamines are much less likely to cause toxicity in youngsters than an initial generation ones, according to a study of much more than 9,000 children.

However, one more study foundthat 2nd generation antihistamines can cause dangerous symptoms when children overdose on them.

Diagnosing an antihistamine overdose usually starts v a discussion around all drugs the human is taking and not just the antihistamines. This is since some various other medications, such together cold, flu, and also sleep medications, contain antihistamines.

If a person takes one of these other medications and also takes one allergy medication, they may accidentally overdose.

Other medications, together as specific antidepressants and motion sickness drugs, can additionally cause an overdose if a person mixes them through antihistamines.

If someone is no sure around the quantity of antihistamine they took, a doctor may need to conduct a physical exam. They might look for indicators such as drowsiness, irritability, blurred vision, or seizures. Lock may also check the love rate, breathing rate, and also blood pressure.

In part cases, a person may require blood tests or more observation in a hospital.

In soft cases, an separation, personal, instance may have the ability to use self-care in ~ home. However, castle should always call the AAPCC or a physician to be certain this is safe.

If the person is experiencing severe symptoms, they may need hospitalization, consisting of heart monitoring, intravenous (IV) fluids, and medication.

In part cases, doctors may provide a human activated charcoal, which helps avoid the absorb of part medications and also chemicals in the gut. Lock may also use ipecac syrup, which reasons the human being to vomit. This can cause any type of excess medication to leave the human body in the vomitus.

Antihistamines may be an initial generation (sedating) or 2nd generation (nonsedating). This two types may lead to various reactions if a human takes also much.

First generation antihistamines are more likely to overcome the blood-brain barrier. This way they deserve to make world dizzy or drowsy, also in common doses.

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

First generation antihistamines obtainable 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 worn down or dizzy.

Some professionals say very first generation antihistamines are much more likely to result in fatality from crashes or overdoses than their 2nd generation counterparts.

Second and third generation antihistamines available over the counter include:

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

These more recent antihistamines are less likely to reason drowsiness and dizziness. Research study has found them less likely to reason dangerous impacts if a human takes too much.

Antihistamines are frequently safe when a human takes the correct amount. However, together with any kind of medication, lock can reason serious adverse impacts if someone takes also much.

People should keep antihistamines and also all medications out of reach of children. Part antihistamines space safe for children to take, however it is necessary to asking a medical professional or pharmacist about the right dose.

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Different antihistamines have various dosages. That is vital to review labels very closely to be certain a human being is no taking as well much.

If one overdose happens, seek prompt medical attention or speak to the AAPCC in ~ 800-222-1222.