Reviewed by Dr. Diana Rangaves, PharmD, RPh
The 4H2 pill contains cetirizine hydrochloride 10 mg, an antihistamine used to relieve common allergy symptoms. Cetirizine can help with sneezing, a runny nose, itchy or watery eyes, and itching of the nose or throat. It is also used to treat hives, also known as urticaria.
If you have found a tablet marked 4H2, identifying it correctly should come before taking it. This guide explains how to identify the 4H2 pill, what cetirizine is used for, how it works, dosage directions, possible side effects, interactions, warnings, and other important safety information.
How to Identify a White Oval Tablet Marked 4H2
U.S. drug-label information identifies the white oval pill marked 4H2 as cetirizine hydrochloride 10 mg. Its imprint and physical features can help distinguish it from other tablets that may look similar.
| Feature | 4H2 Pill Details |
|---|---|
| Imprint | 4H2 |
| Active ingredient | Cetirizine hydrochloride |
| Strength | 10 mg |
| Color | White |
| Shape | Oval |
| Size | About 10 mm |
| Reverse side | Plain |
| Score line | None |
DailyMed describes this tablet as a white, oval 10 mg tablet with “4H2” on one side and a plain reverse. The product record also lists it as unscored and about 10 mm in size.
What Does the 4H2 Imprint Mean?
The marking 4H2 is a pill identification code. It is not the drug name or the dose itself. Instead, the imprint helps identify this specific cetirizine hydrochloride 10 mg tablet.
The imprint is especially important because many medicines may have similar colors or shapes. When identifying an unknown tablet, check the complete imprint and other physical details rather than relying only on color.
What Should You Do If the Pill Does Not Match?
If a tablet has a different imprint, shape, size, or other physical feature, do not assume it is cetirizine simply because it looks similar to the 4H2 tablet. Check the original packaging when possible or ask a pharmacist to identify the tablet before taking it.
Is 4H2 the Same as Zyrtec?
This tablet contains cetirizine, which is also the active medicine in Zyrtec. However, 4H2 is not another brand name for Zyrtec. It is an imprint found on a cetirizine hydrochloride 10 mg tablet.
In simple terms, Zyrtec is a brand name, while 4H2 is a pill imprint. The medicine can contain the same active ingredient even when the brand, packaging, or tablet markings are different.
Is Every Cetirizine Tablet Marked 4H2?
No. The 4H2 imprint refers to a specific cetirizine hydrochloride 10 mg tablet. Cetirizine itself is available in several forms, including regular tablets, chewable tablets, capsules, orally disintegrating tablets, and liquid products.
Therefore, a cetirizine product does not need to have 4H2 printed on it. If you are trying to identify an unknown tablet, use its exact imprint and physical description. For comparison, our L612 pill guide explains how another common allergy tablet is identified as loratadine 10 mg rather than cetirizine.
What Is Cetirizine 10 mg Used For?
Cetirizine 10 mg is used to relieve common allergy symptoms. U.S. OTC labeling lists it for temporary relief of symptoms caused by hay fever and other upper respiratory allergies. The medicine is also widely used for allergic rhinitis, the medical term commonly associated with hay fever and similar nasal allergies.
It may help relieve:
- Runny nose
- Sneezing
- Itchy or watery eyes
- Itching of the nose
- Itching of the throat
Cetirizine helps control these symptoms, but it does not remove the allergen that caused the reaction. If allergy-like symptoms are accompanied by a fever, it may be helpful to understand whether allergies can cause fever, since fever can point to another cause such as an infection.
Can Cetirizine Help With Hives?
Yes. Cetirizine is also used to treat urticaria, commonly called hives. Hives often appear as itchy, raised areas on the skin.
You should not use cetirizine to self-treat hives that are bruised, blistered, unusually colored, or not itchy. You should also contact a doctor if hives do not improve within the first 3 days of treatment or continue for more than 6 weeks.
Cetirizine should not replace emergency treatment for anaphylaxis, which is a serious allergic reaction. If a person has been prescribed an epinephrine injector for possible anaphylaxis, cetirizine should not be used instead of that injector.
How Does Cetirizine Work?
Cetirizine is a second-generation antihistamine. During an allergic reaction, the body releases a substance called histamine, which plays a role in symptoms such as itching, sneezing, a runny nose, and watery eyes.
Cetirizine reduces the effects of histamine at H1 receptors involved in allergic reactions. As a result, common allergy symptoms may become less noticeable. Antihistamines are also commonly used when managing symptoms such as watery eyes, sneezing, and a runny nose, although the right treatment depends on whether symptoms come from allergies, a cold, or another cause. Our guide to the best cold medicine for adults explains these symptom differences in more detail.
How Should Cetirizine 10 mg Be Taken?
According to U.S. OTC cetirizine 10 mg labeling, adults and children 6 years and older are generally directed to take one 10 mg tablet once daily. The label states that they should not take more than one 10 mg tablet in 24 hours. A 5 mg product may be suitable when symptoms are less severe.
General label directions include:
- Adults and children 6 years and older: One 10 mg tablet once daily
- Adults 65 years and older: Ask a doctor
- Children under 6 years: Ask a doctor
- People with liver or kidney disease: Ask a doctor
Cetirizine can be taken with or without food and is generally taken around the same time each day. Always follow the directions on the exact product you are using.
What If You Have Kidney or Liver Disease?
People with kidney or liver disease should speak with a doctor before taking cetirizine because a different dose may be needed. Do not increase or reduce the dose on your own if you have one of these conditions.
How Long Does Cetirizine Last?
Cetirizine hydrochloride 10 mg products are commonly labeled for 24-hour allergy relief, which matches their once-daily directions for eligible users.
However, the effect can vary from one person to another. If symptoms return before the next scheduled dose, do not automatically take another tablet. Follow the dose on the product label or ask a healthcare professional for advice.
What Are the Side Effects of Cetirizine?
Cetirizine can cause side effects, although not everyone who takes it will experience them. Commonly reported effects include:
- Drowsiness
- Excessive tiredness
- Dry mouth
If these effects are severe or do not go away, speak with a healthcare professional. You should also report unusual symptoms that appear while using the medicine.
What Serious Reactions Need Medical Attention?
Serious allergic reactions can require urgent medical care. Warning signs may include trouble breathing or swallowing, swelling in or around the mouth, swelling of the tongue, wheezing, severe dizziness, or loss of consciousness.
If someone has serious breathing problems, collapses, becomes unresponsive, or shows other signs of a medical emergency, seek emergency medical care immediately.
Does Cetirizine Cause Drowsiness?
Yes. Cetirizine can make some people sleepy because it may cause drowsiness. U.S. OTC labeling advises users to be careful when driving a motor vehicle or operating machinery until they know how the medicine affects them.
The level of drowsiness can vary. Some people may notice very little effect, while others may feel tired or less alert. Cetirizine is a second-generation antihistamine, but drowsiness is still a known possible side effect.
Can You Drink Alcohol While Taking Cetirizine?
U.S. cetirizine labeling advises users to avoid alcoholic drinks. Alcohol can increase the drowsiness caused by cetirizine, which may reduce alertness and make activities such as driving less safe.
Even if cetirizine causes little sleepiness on its own, combining it with alcohol may make the sedating effect stronger.
Does Cetirizine Interact With Other Medicines?
Cetirizine labeling specifically advises people taking sedatives or tranquilizers to ask a doctor or pharmacist before using the medicine because these drugs can increase drowsiness.
You should also tell your healthcare provider about other products you use, including:
- Prescription medicines
- Over-the-counter medicines
- Vitamins
- Nutritional supplements
- Herbal products
A doctor or pharmacist can check whether your medicines may need dose changes or closer monitoring for side effects.
Who Should Not Take Cetirizine?
Do not use cetirizine if you have previously had an allergic reaction to cetirizine, any ingredient in the product, or an antihistamine containing hydroxyzine.
If you are unsure whether a previous reaction was linked to one of these medicines, ask a doctor or pharmacist before taking this cetirizine tablet.
Can You Take 4H2 During Pregnancy or Breastfeeding?
According to U.S. OTC labeling, people who are pregnant should ask a health professional before using cetirizine. The reviewed label states that use while breastfeeding is not recommended.
Pregnancy and breastfeeding decisions depend on individual health factors, so a healthcare professional can provide guidance based on the person’s situation.
Can Stopping Cetirizine Cause Severe Itching?
Yes, although this reaction appears to be rare. The FDA has warned about severe itching, also called pruritus, after stopping long-term cetirizine or levocetirizine use. Reported cases generally involved daily use for several months or years, and the itching usually began within a few days after the medicine was stopped.
The FDA identified 209 reported cases worldwide, including 197 in the United States, in the data it reviewed. The median time for itching to begin after stopping the medicine was 2 days.
People who develop severe itching after stopping cetirizine should contact a healthcare professional. Anyone planning to use cetirizine regularly for more than a few months should also discuss the benefits and risks of long-term use with a healthcare professional.
What Happens If You Take Too Much Cetirizine?
Taking more cetirizine than directed can be unsafe. If an overdose happens, the product label advises getting medical help or contacting a Poison Control Center right away. Do not take extra tablets to make the medicine work faster or provide stronger allergy relief, because taking more than directed can increase the risk of unwanted effects.
Possible overdose symptoms can include:
- Restlessness
- Irritability
- Drowsiness
If a person collapses, has a seizure, has trouble breathing, or cannot be awakened, emergency medical help is needed.
What Should You Do If You Miss a Dose?
If you forget a cetirizine dose, take it when you remember unless it is almost time for the next scheduled dose. If the next dose is due soon, skip the missed dose and return to your usual schedule. Do not take a double dose to make up for a missed tablet.
This helps prevent doses from being taken too close together.
How Should You Store Cetirizine?
The reviewed 4H2 product label recommends storing the tablets between 20°C and 25°C (68°F to 77°F). The label also advises against using a bottle if its safety seal is broken or missing.
Keep cetirizine in its original container, tightly closed, and out of children’s reach. It should also be kept away from excess heat and moisture.
Who Labels or Packages the 4H2 Tablet?
Drug-identification records associate Perrigo Company with the 4H2 cetirizine hydrochloride 10 mg tablet as a labeler or supplier. DailyMed also lists PD-Rx Pharmaceuticals, Inc. as the packager and labeler of a repackaged cetirizine hydrochloride product carrying the 4H2 imprint.
Because medicines can be packaged or repackaged by different companies, the bottle or retail packaging may vary. For pill identification, the imprint and physical characteristics of the tablet are more useful than relying only on the package design.
What Ingredients Are in This Cetirizine Tablet?
The active ingredient in this tablet is cetirizine hydrochloride 10 mg. Inactive ingredients are also used to make, coat, and stabilize the tablet.
The reviewed product lists ingredients such as:
- Corn starch
- FD&C Blue No. 1 aluminum lake
- Hypromellose
- Lactose monohydrate
- Magnesium stearate
- Polydextrose
- Polyethylene glycol
- Povidone
- Titanium dioxide
- Triacetin
Inactive ingredients can vary between products. Anyone with a known ingredient allergy or sensitivity should check the label of the exact product they plan to use.
Is Cetirizine 10 mg Available Over the Counter?
Yes. The reviewed 4H2 cetirizine hydrochloride 10 mg product is classified as a human OTC drug, meaning it is sold without a prescription in the United States.
However, over-the-counter status does not mean the medicine is suitable for everyone. Follow the product-label dose and warnings.
Is 4H2 a Controlled Substance or Narcotic?
No. The tablet is not classified as a controlled substance or narcotic. Cetirizine belongs to the antihistamine drug class rather than the opioid or narcotic drug classes.
Even though it is not a controlled substance, cetirizine should still be taken according to product directions.
Can the 4H2 Pill Get You High?
This pill is not intended to produce a high. Cetirizine is an antihistamine used for allergy symptoms rather than an intoxicating drug. Taking more than directed can be unsafe and may increase unwanted effects such as drowsiness, restlessness, or irritability.
Final Thoughts
The 4H2 pill contains cetirizine hydrochloride 10 mg, an antihistamine used to relieve allergy symptoms and hives. If you find an unknown tablet, confirm its imprint and physical details before taking it rather than relying only on color or shape.
Cetirizine can provide useful allergy relief when taken as directed, but safe use still matters. Follow the product-label dose, understand possible drowsiness and interactions, and seek professional advice when medical conditions, pregnancy, breastfeeding, other medicines, or long-term use could affect treatment.
The FDA’s warning about rare severe itching after stopping long-term cetirizine use is also important for regular users to know. If you are unsure whether a tablet is really the 4H2 pill or whether cetirizine is suitable for you, ask a pharmacist or another qualified healthcare professional rather than guessing.
Sources
- Cetirizine Hydrochloride – DailyMed
- 24 Hour Allergy – DailyMed
- Cetirizine – MedlinePlus
- Cetirizine Safety Warning – FDA
- Cetirizine – NCBI Bookshelf
- 4H2 Pill Identifier – Drugs.com
This article is for general educational purposes only and does not replace professional medical advice, diagnosis, or treatment.