Antihistamines: Zyrtec vs Claritin, Drowsiness and Use in Children

Antihistamines are medicines that relieve allergy sneezing, runny nose, and itchy eyes and skin. The best-known are Zyrtec (cetirizine) and Claritin (loratadine). Both are classified as "non-drowsy," but some people do feel sleepy on them, and Zyrtec is more likely to cause this. In children, the dose is set by weight and by a doctor's prescription or pharmacist's guidance. During pregnancy, they are used only with a doctor's approval [1] [4].

What Are Antihistamines and Why Do We Use Them?

When exposed to an allergen such as dust, pollen, or animal fur, the body releases histamine, and the familiar symptoms appear. These medicines reduce the effect of this substance, so the symptoms settle.

The UK's National Health Service (NHS) states that cetirizine is used for hay fever (seasonal allergy), conjunctivitis causing red and itchy eyes, eczema, hives (urticaria), insect bite and sting reactions, and some types of food allergy [1]. Loratadine is used for largely the same purposes [4].

Both medicines are available as tablets and as a liquid to be swallowed, and they can be bought from pharmacies or obtained with a prescription [1] [4]. They relieve symptoms but do not treat the underlying cause of the allergy.

Important note: Brand names differ from country to country, and some products with the same name contain a different active ingredient [1]. Therefore, read the active ingredient on the box and do not rely on the brand name alone.

What Is the Difference Between Zyrtec and Claritin?

Zyrtec (Zyrtec drug page in the drug directory) has cetirizine as its active ingredient. The same substance appears under the name Zyrtec in the directory. Claritin has loratadine as its active ingredient.

The two medicines are similar in how they are used, but there are practical differences, shown in the table:

The difference in dose adjustment relates to how the body eliminates the medicine. Zyrtec is excreted through the kidneys, while loratadine is metabolized in the liver, according to the Clinex Go drug guide. Therefore, it matters that your doctor and pharmacist know whether you have a kidney or liver condition.

Do Antihistamines Cause Drowsiness?

These medicines are usually divided into older sedating types and newer "non-drowsy" types. The NHS describes both cetirizine and loratadine as non-drowsy, meaning they are much less likely to make you feel sleepy than some other antihistamines [1] [4].

However, "non-drowsy" does not mean "never causes drowsiness." Drowsiness and tiredness are the most common side effects of cetirizine [3]. Some people also feel slightly sleepy from loratadine [4].

The Clinex Go drug guide puts the rate of drowsiness with Zyrtec at about 10%, and with Claritin at about 2%. Anyone whose job does not allow any drowsiness should ask the pharmacist which option is most suitable.

What Should You Do If You Feel Drowsy?

• Try the medicine for the first time in the evening, and watch how your body responds before any activity that requires alertness.
• Ask the pharmacist or doctor for a non-drowsy alternative instead of changing the medicine yourself. This is what the NHS recommends when drowsiness occurs [3].
• Avoid alcohol, as it may increase drowsiness with loratadine [4]. According to the drug guide, it may also increase drowsiness with Zyrtec and with sedatives.
• Do not combine two antihistamines without asking the pharmacist.

Other common side effects include headache, dry mouth, nausea, dizziness, and diarrhea [3]. Chewing sugar-free gum may relieve dry mouth, and taking the tablet with food may relieve nausea [3].

Can You Drive After Taking These Medicines?

The principle is to know how the medicine affects you before you drive. If you feel drowsy, do not drive a car or ride a bicycle [1] [4]. If you feel dizzy or have slight tremors, do not drive or use tools or machinery [3].

Assessing yourself is part of safe use. Try the medicine once at a time when you do not need to drive. If it does not affect you, future use will usually be easier, but always monitor yourself, especially when taking alcohol or sedatives.

If you need to go to the emergency room due to an overdose or worrying symptoms, do not drive yourself. Ask someone to take you or call an ambulance (911), and bring the medicine box and any other medicines you are taking [2].

How Are Antihistamines Used in Children?

A child's dose is more sensitive than an adult's dose and should not be estimated by guesswork. It is always based on weight and given by a doctor's prescription or pharmacist's guidance, and what is written on the box of the product you have in hand should always be followed.

Here are the key points from the sources:

• Children under 12 years take cetirizine at a lower dose twice daily [1]. It is preferable to leave a gap of 10 to 12 hours between doses [2].
• For a child aged one year, the doctor calculates the dose based on weight or age [2].
• For loratadine, the doctor calculates the dose based on weight or age. Children aged 6 to 12 years take tablets only if their weight exceeds 30 kg. Children under 6 years or weighing 30 kg or less take the liquid [5].
• The minimum age differs between products. The Clinex Go guide lists 6 months for Zyrtec and 2 years for Claritin. In all cases, refer to the box leaflet and the pharmacist.

The liquid is often easier for a child than tablets, and it comes with a syringe or measuring spoon. Do not use a kitchen spoon, as it does not give the correct amount. Ask the pharmacist for a syringe if one is not provided [2] [5].

Children may experience side effects that differ from those in adults. Diarrhea, sneezing, and nasal congestion or runny nose are more common in them with cetirizine [3]. A child may experience headache, tiredness, or irritability after loratadine [4]. Sometimes some children become more agitated instead of drowsy, according to the drug guide.

If your child takes more than the recommended dose, call the doctor or pharmacist immediately, even if no symptoms appear, especially if the child is under 5 years old [2] [5]. If severe symptoms appear, go to the emergency room or call 911.

For more on managing your child's allergy, see the allergy in children treatment service and the article Food Allergy in Children.

Are These Medicines Safe During Pregnancy and Breastfeeding?

The Clinex Go drug guide classifies both cetirizine and loratadine as pregnancy category B. It states that they are among the studied options and relatively safer when needed and with a doctor's approval. Details are on the Zyrtec and Claritin pages.

However, this does not mean a pregnant woman should take them without consultation. Each case needs assessment: the severity of symptoms, whether non-drug measures such as saline nasal rinses are sufficient, and the presence of other conditions. Similarly, ask your doctor or pharmacist about breastfeeding before use, as the sources cited here do not address this point.

Should You Combine Tablets with Nasal Sprays for Seasonal Allergy?

Often, yes. The drug guide notes explain that chronic nasal allergy cannot be managed with a tablet alone. Saline nasal rinses and nasal corticosteroid sprays improve the outcome when symptoms persist. If Claritin alone is not enough during the dust season, it is better to add a rinse and a spray rather than doubling antihistamines.

The role of each is different:

• Tablet or liquid: relieves sneezing, runny nose, and itching of the nose and eyes.
• Saline rinse: cleans irritants and mucus from the nose.
• Nasal corticosteroid spray: calms nasal inflammation when symptoms are persistent. It is prescribed by a doctor or pharmacist, and the correct way to use it should be reviewed.

For a season that recurs every year, a doctor can help set up a plan before the season starts. The sources note that the medicine may be taken for a short period or when symptoms appear, or regularly to prevent hay fever [2] [5]. To learn the difference between allergy and a cold, and about the spray plan, see the article Nasal Allergy: How It Differs from a Cold and Proper Treatment.

When Should You See a Doctor, and When Should You Go to the Emergency Room?

See a doctor if:

• Symptoms persist despite following treatment, or you need the medicine every season.
• Hives recur for more than 6 weeks, as this deserves an assessment rather than switching boxes. See also What to Do If Chronic Hives Do Not Improve.
• You notice bruises that are easier than usual or bleeding that takes a long time to stop. These are rare but serious side effects [3].
• You notice bothersome symptoms that do not go away, such as severe drowsiness or dizziness.

Go to the emergency room or call 911 immediately if:

• The lips, mouth, throat, or tongue suddenly swell.
• You are breathing fast or with difficulty, or you feel tightness in the throat or difficulty swallowing.
• The color of the skin, tongue, or lips turns blue, gray, or pale.
• You suddenly become confused, very drowsy, or dizzy, or someone faints and does not wake up.
• The child appears limp or does not respond as usual.

These are signs of severe allergy (anaphylaxis) that may require immediate hospital treatment, and you should not drive yourself [3]. Tablets alone are not enough to treat it, as explained in this common question.

How Do You Find the Right Doctor or Clinic in Jordan?

If the allergy is persistent or severe, or affects sleep, work, or study, the appropriate specialty is allergy and immunology. Browse allergy and immunology doctors in Jordan, then narrow your search by governorate, including Amman, Irbid, and Zarqa, as well as other governorates on the specialty page.

When reading a doctor's or clinic's profile, check:

• The specialty and experience listed, and whether they include children if the patient is a child.
• The location and working hours, and the means of contact or booking if available in the profile.

Questions to ask at the appointment:

1. What are the likely triggers for my allergy, and do I need tests?
2. Which antihistamine suits my work, my driving, and my age or my child's age?
3. Do I need a nasal rinse or spray, and when should I start using it?
4. When are symptoms considered an emergency in my case?

The directory lists profiles to help you choose. It does not provide medical advice or prescriptions. If you need an antihistamine during pregnancy or for a child, ask a doctor or pharmacist before starting.

Frequently asked questions

Which is better for allergies: Zyrtec or Claritin?

No single medicine is best for everyone. Both relieve allergy sneezing and itching of the nose and eyes, but Zyrtec may cause more drowsiness in some people, and Claritin is usually milder in this respect. The choice depends on your work, your age, and your other conditions, so ask a pharmacist or an allergy doctor.

Can I take Zyrtec or Claritin and then drive?

Do not drive if you feel drowsy, dizzy, or shaky after either one. Try the medicine for the first time at a time when you do not need to drive, and monitor how it affects you. Avoid alcohol with it, and if worrying symptoms appear, ask someone to take you to the emergency room.

What is the right antihistamine dose for my child?

There is no single dose for everyone. A child's dose is set by weight and age, based on a doctor's prescription or pharmacist's guidance, and it differs between products. The liquid is usually preferred with the measuring syringe provided, and a kitchen spoon should not be used. If a child takes more than prescribed, call the doctor or pharmacist immediately.

Are antihistamines safe during pregnancy?

The Clinex Go drug guide classifies Zyrtec and Claritin as pregnancy category B, and describes them as studied options when needed. However, pregnant women should take them only with their doctor's approval after assessing their symptoms, and should also consult their doctor before use during breastfeeding.

Is a tablet alone enough for seasonal nasal allergy?

It may be enough in mild cases, but chronic or severe nasal allergy usually needs a broader plan. A saline nasal rinse is commonly added, along with a nasal corticosteroid spray prescribed by a doctor or pharmacist if symptoms persist, rather than doubling antihistamines. If symptoms continue, consult an allergy doctor.

When is an allergy an emergency?

Go to the emergency room or call 911 if sudden swelling of the lips, tongue, or throat appears, or if there is difficulty breathing or swallowing, bluish skin, confusion and fainting, or severe limpness in a child. These are signs of severe allergy, and tablets alone are not enough to treat them.

Sources and references

1. About cetirizine — NHS (UK National Health Service). Accessed: 2026-10-26.
2. How and when to take cetirizine — NHS (UK National Health Service). Accessed: 2026-10-26.
3. Side effects of cetirizine — NHS (UK National Health Service). Accessed: 2026-10-26.
4. About loratadine — NHS (UK National Health Service). Accessed: 2026-10-26.
5. How and when to take loratadine — NHS (UK National Health Service). Accessed: 2026-10-26.