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Updated on January 26, 2023
6 min read

Hydroxyzine Overdose

What is Hydroxyzine (& What Does it Treat)?

Hydroxyzine Pamoate is in a class of medicines called antihistamines. It's a first-generation antihistamine with weak sedative, anticholinergic, and antiemetic properties. The drug is also sold under the brand names Atarax and Vistaril.

Hydroxyzine blocks histamine, the substance in the body that leads to allergic symptoms. It also decreases activity in the central nervous system (CNS). Because of this, it's often used to treat:

  • Hives from allergies
  • Anxiety and tension in adults and children
  • Sedation before and after general anesthesia for surgery.

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Can You Overdose on Hydroxyzine?

Yes, it’s possible to overdose on hydroxyzine. Hydroxyzine overdose occurs when an individual takes more than the usual or recommended amount of the medication. This can be done by accident or intentionally.

Allergy medications like hydroxyzine are safe and can quickly relieve symptoms when used correctly. However, an antihistamine overdose can be life-threatening, so understanding proper dosing is essential to avoid toxicity.

Symptoms of Hydroxyzine Overdose

Below is the full list of the vital signs of a hydroxyzine overdose:

  • Dilated pupils
  • Shortness of breath
  • Difficulty urinating
  • Blurred vision
  • Dry mouth
  • Enlarged pupils
  • Dry eyes
  • Ringing in the ears
  • Rapid heartbeat
  • Low blood pressure
  • Pounding heartbeat (palpitations)
  • Agitation
  • Coma
  • Lack of responsiveness
  • Decreased level of consciousness
  • Seizures
  • Delirium
  • Depression
  • Disorientation 
  • Dizziness
  • Sleepiness
  • Excitation
  • Hallucinations
  • Nervousness
  • Tremor
  • Uncoordinated movement
  • Unsteadiness
  • Dry, red, or flushed skin
  • Nausea
  • Vomiting

How Long Do Overdose Symptoms Last?

It is challenging to predict when an overdose may occur or how long it will last. The length of overdose symptoms depends on various factors, such as: 

  • How much hydroxyzine was taken
  • Your body weight 
  • Your size

If you are concerned about a potential overdose, seek medical attention immediately. Symptoms don't go away on their own. Overdoses are almost always fatal without proper help. 

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Is Hydroxyzine Overdose Dangerous? 

Recovery from a hydroxyzine overdose is likely if the person survives the first 24 hours. However, the following complications may lead to permanent disability:

  • Pneumonia
  • Muscle damage from lying on a hard surface for an extended period
  • Brain damage from a lack of oxygen

Can You Die From Hydroxyzine Overdose?

Few people die from an antihistamine overdose unless they have severe heart rhythm disturbances or breathing issues. However, some deaths have occurred due to antihistamine toxicity, whether accidentally or intentionally.

Each individual has varied tolerance to antihistamines. However, toxicity typically occurs when a person consumes three to five times the recommended dosage.

Deaths typically occur when a hydroxyzine overdose leads to severe complications, including:

  • Respiratory distress
  • Cardiac arrest
  • Seizures

Proper Hydroxyzine Dosage

Usually, hydroxyzine is taken three or four times a day. Follow the directions on the prescription label correctly. Ask your doctor or a healthcare professional to explain any parts of the treatment you don’t understand.

It’s available in the following forms:

  • Capsules
  • Tablets
  • Syrup
  • A suspension (to take by mouth)

Antihistamines like hydroxyzine are safe when taken correctly. If you take hydroxyzine by suspension, shake it well before use to mix the solution evenly.

What to Avoid When Taking Hydroxyzine

Don’t consume more or less hydroxyzine or take it more often than your doctor prescribes. Here are some tips and advice to avoid overdose:

  • Don’t double up on doses
  • Keep the drugs out of reach of children
  • Do not take two doses too close together
  • Ensure you read labels carefully

This drug shouldn't be used for more than 4 months. Contact your doctor if your symptoms don't improve in this timeframe.

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Hydroxyzine Side Effects

Taking hydroxyzine may result in side effects and risks. Speak with your doctor or a healthcare professional if any of the following symptoms are severe or persist after ingestion:

  • Dry mouth
  • Constipation (especially in older adults)
  • Confusion (especially in older adults)
  • Dizziness
  • Headache
  • Hypotension
  • Hypersensitivity 

Some side effects can be more serious. They include:

  • Unintentional trembling or shaking movements
  • Seizures 
  • Pus-filled rash, blister-like sores, or lesions
  • Areas of redness or swelling on the skin
  • Fever

Who is at Risk When Taking Hydroxyzine?

Let your doctor know about any abnormalities while taking this medicine. You should also speak with your doctor before taking the drug if you have glaucoma. 

There are also precautions for its use in:

  • Pregnant women
  • Those who have recently had a heart attack
  • Those with slow or irregular heartbeats
  • Those with low or high potassium levels

Drugs to Avoid While Taking Hydroxyzine

Hydroxyzine can interact with other drugs and alter how your medications work. It can also increase the risk of severe side effects. Talk to your doctor about any prescription or non-prescription drugs and herbal supplements that you use.

Check the disclaimer labels on your medications, especially for allergy or cough-and-cold products. They may contain ingredients that lead to drowsiness. Drugs that may cause drowsiness include:

  • Opioid pain or cough relievers, such as codeine or hydrocodone
  • Alcohol
  • Marijuana (cannabis)
  • Medicines for sleep or anxiety, like alprazolam, lorazepam, or zolpidem
  • Muscle relaxants, like carisoprodol or cyclobenzaprine
  • Other antihistamines, like diphenhydramine or promethazine
  • Drugs that can prolong QT interval
  • Class III antiarrhythmics
  • Some antimalarials (e.g., mefloquine)
  • Some antibiotics (e.g., erythromycin, levofloxacin)
  • Gastrointestinal agents (e.g., prucalopride)
  • Anti-cancer drugs (e.g. toremifene, vandetanib)

Don't use hydroxyzine with other antihistamines applied to the skin, like diphenhydramine. It may increase the risk of severe side effects.

When to Visit the ER

If someone is experiencing the following symptoms, they must visit the emergency room:

  • Rapid heart rate
  • Chest tightness
  • Convulsions

However, some side effects and symptoms of taking antihistamines can mimic a drug overdose. These side effects don’t usually require medical attention. They may subside as your body adjusts to the medicine. 

These side effects include:

  • Mild nausea
  • Dizziness
  • Vomiting
  • Diarrhea
  • Stomach pain

The difference between side effects and an overdose is usually the severity of symptoms. However, it’s always best to check with a doctor if you have side effects. You may need to adjust your dosage or take a different medicine.

What Should You Prepare Before Calling the ER?

Before calling for emergency help, have the following information ready:

  • The individual’s age, weight, and condition
  • Name of the medication, including ingredients and strength if known
  • Time the medicine was swallowed
  • Amount of medicine swallowed
  • Whether the medicine was prescribed for the individual
  • If possible, bring the antihistamine product to the hospital with you

Antihistamine Overdose Treatment

Antihistamine overdose treatment stabilizes the individual’s health and provides supportive care. Tests that may be performed during an antihistamine overdose include:

  • Blood and urine tests 
  • Chest x-ray ECG (electrocardiogram or heart tracing)

You'll likely receive activated charcoal in the hospital. It stops the absorption of toxins and chemicals from entering the body from the stomach. Toxins then bind to the charcoal and leave the body through bowel movements.

Treatment Options for Antihistamine Overdose

Other treatments may include: 

  • Fluids through a vein (by IV) 
  • Medications to treat symptoms 
  • Laxatives
  • Breathing assistance, including a tube through the mouth into the lungs and connected to a ventilator


Hydroxyzine Pamoate is in a class of medicines called antihistamines. It's often used to treat allergies, anxiety, and tension.

You can overdose on hydroxyzine when you take more than the recommended dosage. It's important to understand the symptoms of an overdose because it can be life-threatening.

Hydroxyzine can also interact with other drugs and cause complications or severe side effects. Speak to your doctor about your prescribed and non-prescribed medications before taking hydroxyzine.

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Updated on January 26, 2023

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