How long does Piriton take to work?

Piriton is an over-the-counter anti-allergic medication containing chlorpheniramine, the active ingredient. According to the British National Formulary (BNF), chlorpheniramine can provide symptomatic relief from hay fever, food allergies, drug reactions, urticaria (hives), and chickenpox itch. Due to its quick onset of action, there has been an increased demand for Piriton in the UK, particularly in winter.

According to the National Health Services (NHS), it takes only 30 minutes to one hour to start its function in the body.

Time of action

When taken orally, Piriton is well absorbed in the gut. After absorption, its function starts within thirty minutes to one hour. Its action reaches its peak within 1 to 2 hours of intake. It reduces the action of certain allergy-causing chemicals, such as histamine, leukotrienes, and prostaglandins. These chemicals are responsible for producing inflammation and allergy symptoms.

Usually, the effects of Piriton last only 4 to 6 hours. Afterwards, it is converted into inactive metabolites (substances produced as a result of a medication breakdown) and eliminated from the body via urine.

Difference in the onset of action between syrup and tablet

There’s no reported difference in the onset of action between Piriton tablets and Piriton syrup. However, the syrup is usually used in children, while tablets are used in adults.

Alcohol intake while taking Piriton

Alcohol can slow down the metabolism of Piriton and exacerbate its side effects related to the nervous system, such as dizziness, drowsiness, difficulty concentrating, and confusion. That is why it is better to avoid alcohol while taking Piriton.

Just like alcohol, Piriton should also not be combined with certain medications, including Phenytoin (anti-epileptic medicine) and antidepressants.

When should you avoid Piriton?

Piriton is not recommended in adults with chlorpheniramine allergy, primary angle glaucoma (an eye condition with increased fluid levels in the eye), epilepsy, and problems with emptying the bladder.

It should be used cautiously in the elderly because it can increase confusion and sedation in old age. Moreover, the manufacturer states that you should use it after consulting with a healthcare professional if you have asthma, kidney problems, or high blood pressure.

In addition, it is better to avoid Piriton if you plan to drive or work near heavy machinery in the next 4-6 hours because it can cause drowsiness.

Frequently Asked Questions (FAQs)

Recommended waiting time to take the next dose?

Piriton is a sedating medication that requires a recommended gap between the two doses. According to the NHS, you should wait at least 4-6 hours before taking the next dose.

How many Piriton tablets can be used daily?

Piriton (4mg) can be taken four times daily; however, it should only be taken when needed or as prescribed by a licensed healthcare professional.

Is it safe for long-term use?

NHS recommends against using Piriton for more than two weeks if purchased over the counter without discussing it with a healthcare professional.

Authored By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist

Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Published on: 02/08/2024

Reviewed By

Dr Giuseppe Aragona

Doctor

Dr. Giuseppe utilises his extensive experience in general practice to ensure the accuracy and safety of the website's content.

Reviewed on: 02/08/2024