If you take too much ZYRTEC you may be more likely to have side effects such as: confusion, diarrhoea, dizziness, tiredness, headache, malaise, dilating of pupil, itching, restlessness, sedation, somnolence (feeling drowsy), stupor, abnormal rapid heart rate, tremor, urinary retention.
Cetirizine is generally very safe. Taking more than the usual dose is unlikely to harm you or your child. If you take an extra dose, you might get some of the common side effects. If this happens or you're concerned, contact your doctor.
Adults and children 6 years and older Chew and swallow 2 tablet (10 mg) once daily; do not take more than 1 tablet (10 mg) in 24 hours. A 5 mg product may be appropriate for less severe symptoms.
Don't take more than 1 tablet in 24 hours. Children's Zyrtec (ages 2+) chewable tablets contain 2.5 mg of cetirizine per tablet. If you are under 65 years old, chew and swallow 2 to 4 tablets (5 mg to 10 mg) once daily. Don't take more than 4 tablets in 24 hours.
Overdose Signs
Overdose symptoms may include severe drowsiness, vision problems, agitation, fast heartbeats, stomach pain, nausea, vomiting, trouble walking, trouble swallowing or speaking.
Toxic doses of antihistamines may happen when a person takes 3 to 5 times the normal amount. No matter how much a person overdoses, they should seek medical help or call a poison control center.
ZYRTEC 10 mg film-coated tablets
Others may need to take 20 mg, e.g. larger people or those who find that 10 mg is not enough. The maximum recommended daily dose is 20 mg, do not exceed this dose, unless told to do so by your doctor.
It's natural to worry if you realize you've accidently doubled your dose, but in most cases, you won't need to do anything if you mistakenly take two pills. Even children usually don't need treatment after a double dose. Just manage any symptoms you or your child has.
Medically reviewed by Drugs.com. Last updated on Oct 18, 2021. take 1 tablet every 12 hours; do not take more than 2 tablets in 24 hours.
Why do antihistamines stop working? Antihistamines can stop working because your allergies might be getting worse or you might have immune system changes due to aging. You also might not be taking the medication as directed. If you take an antihistamine after being exposed to an allergy trigger, it won't work as well.
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The elimination half-life of Zyrtec is between 8 to 9 hours. It takes approximately 5.5 x elimination half-life for a medicine to be cleared from your system. For Zyrtec this is 5.5 x 9 hours which is about 2 days.
Zyrtec. Zyrtec (cetirizine) is the strongest of the second-generation antihistamines, says Dr. Garcia-Ibáñez. And because there is less chance of toxicity with this medication, the dosage can be increased substantially, at the discretion of your doctor, he says.
Cetirizine can be taken at any time of the day. In most people it is non-sedating, so they take it in the morning. However, a percentage of people do find it to be sedating so if it does make you drowsy it is best to take it in the evening. Cetirizine can be taken with or without food.
The most common dose contains 25 mg of diphenhydramine in each tablet or capsule. This is the formulation we'll be discussing here. The recommended adult Benadryl dosage for allergies is 1 to 2 tablets or capsules by mouth every 4 to 6 hours as needed. You shouldn't take more than 6 doses (300 mg) in a 24-hour period.
Oral antihistamines, such as Zyrtec and Benadryl, shouldn't be taken together without a healthcare provider's OK. Taking oral antihistamines together can lead to additional side effects and potentially an antihistamine overdose. Signs of an overdose may include the following: Fast or racing heartbeat.
In overdose symptoms can include dizziness, tachycardia, headache drowsiness or agitation. While the current generation of lesser sedating antihistamines do not affect the QT interval at normal doses (unlike the previous generation of medicines), there are concerns there may be some effect in overdose.
Taking 10mg of Zyrtec is more effective than taking 5mg; taking 20mg appears not to provide any additional effect. Food has no effect on the overall absorption of Zyrtec; however, it may increase the time it takes for peak levels of Zyrtec to be reached in the blood.
Tell your doctor or pharmacist if you are taking other products that cause drowsiness such as opioid pain or cough relievers (such as codeine, hydrocodone), alcohol, marijuana (cannabis), drugs for sleep or anxiety (such as alprazolam, lorazepam, zolpidem), muscle relaxants (such as carisoprodol, cyclobenzaprine), or ...
Any time of day works. And ZYRTEC® will continue to work for 24 hours.
Antihistamines that can cause weight gain include: Diphenhydramine (Benadryl and others) Cetirizine (Zyrtec) Levocetirizine (Xyzal)
“Zyrtec is found to be more potent, or stronger, in laboratory studies, compared with Claritin,” says Dr. Kung. “It also reaches a higher concentration in the skin, which can be more helpful for skin-related allergies. However, Zyrtec has a greater chance of making you sleepy while taking it.”