Understanding Antihistamines in Singapore: A Comprehensive Guide to Chlorpheniramine

Understanding Antihistamines in Singapore: A Comprehensive Guide to Chlorpheniramine

An allergy occurs when an individual’s immune system overreacts to usually non-harmful substances. These substances, also known as allergens, typically include:

  • Dust mites
  • Pets or animal dander
  • Pollen
  • Insects
  • Mould
  • Certain foods
  • Certain medications

When the immune system overreacts to these allergens, it mounts an immune response that involves the release of immune cells and chemicals such as histamines, causing inflammation and symptoms such as redness, swelling, and itchiness.

While there are many different types of allergies, it is estimated that less than 5% of children below 12 years of age suffer from food allergies, and the prevalence declines as age increases to about 1% in adults.

A study on allergic rhinitis in Singapore and Malaysia reported that allergic rhinitis was observed in almost 40% of the studied population, and this prevalence also decreases with increasing age.

This article explores the use of antihistamines such as chlorpheniramine for allergies and how Glovida-Rx, a trusted online pharmacy, can simplify access to allergy medications.

What Are Antihistamines?

In allergic reactions, the immune system releases histamines due to an overreaction to usually non-harmful substances. The release of histamines causes symptoms such as itching and difficulty breathing due to constriction of the airways.

In severe cases, histamines may cause potentially fatal anaphylaxis. In these cases, airways can become swollen, hindering breathing, and there may be a sudden blood pressure crash, affecting blood supply to vital organs.

Antihistamines are medications that are most commonly used to treat symptoms associated with allergies by blocking the effects of histamines. There are 2 main types of antihistamines:

1. First generation

First-generation antihistamines are less selective to histamine receptors compared to second-generation antihistamines. They also cross the blood-brain barrier, contributing to side effects such as sedation, drowsiness, fatigue and impaired alertness. Examples of first-generation antihistamines include:

2. Second generation

The newer second-generation antihistamines are more selective to histamine receptor blockage and generally do not cross the blood-brain barrier, thereby having a more favourable side effect profile than first-generation antihistamines. Examples of the second generation antihistamines include:

Chlorpheniramine Explained

Chlorpheniramine is a first-generation antihistamine indicated for allergic conditions. A conventional 4 mg chlorpheniramine tablet can be taken every 4 to 6 hours daily as needed. It does not treat the cause of allergies or speed up recovery but helps to relieve the associated symptoms such as sneezing, itchiness, or runny nose. For the allergy to be treated completely, the trigger or cause of allergy has to be identified and avoided.

Using Chlorpheniramine in Singapore

Chlorpheniramine is a Pharmacy-Only medication in Singapore. It can be purchased through a pharmacist. It is recommended that you consult a healthcare professional prior to starting a new medication.

Glovida-Rx, a reliable online pharmacy in Singapore, offers convenient access to medications such as chlorpheniramine. Additionally, Glovida-Rx emphasizes personalized care and provides complimentary consultations with expert pharmacists. To ensure the safe use of medications, it is vital to follow the instructions and advice of qualified healthcare professionals, so do not hesitate to contact us if you have any queries.

Side Effects and Precautions

As with all medications, chlorpheniramine may also cause some side effects. Common side effects include but are not limited to:

  • Drowsiness
  • Dry mouth, nose and throat
  • Nausea and vomiting
  • Loss of appetite
  • Constipation
  • Headache

As chlorpheniramine may cause drowsiness, it is advisable to avoid driving or operating machinery when taking the medication. Contact your healthcare professional should these side effects become severe or do not go away.

Individuals with certain health conditions should take special precautions and consult their healthcare professional before taking chlorpheniramine. These health conditions include but are not limited to:

  • Heart conditions such as ischemic heart disease or high blood pressure
  • Increased intraocular pressure or glaucoma
  • Thyroid dysfunction
  • Asthma or bronchitis
  • Genitourinary obstruction

If you have any doubts, feel free to contact Glovida-Rx for a free consultation with our pharmacists.

Alternatives to Chlorpheniramine

While chlorpheniramine can manage symptoms associated with allergic conditions, it may not be the most suitable choice for everyone. A variety of antihistamines are available in Singapore, ranging from drowsy first-generation antihistamines to non-drowsy second-generation antihistamines.

The choice of antihistamines depends on many factors, such as personal preference for brands, side effect profile, and severity of symptoms. Glovida-Rx provides a wide selection of antihistamines to cater to different individuals, and you can check them out here. If you encounter any difficulties deciding which antihistamine best suits your needs, feel free to consult our pharmacists at +65 8101 5555.

Living with Allergies in Singapore

Although antihistamines can alleviate symptoms associated with allergic conditions, it is also beneficial to adopt a preventive approach. 

Management and Preventive measures

  • Identify and avoid allergens

Be aware of what triggers your allergic symptoms and try to avoid these allergens. For example, if you notice that you may be allergic to dust mites or dust, try using High-efficiency Particle Air (HEPA) filter vacuum cleaners and washing your bedding more often in hot cycles (60°C).

  • Keep a diary

Keeping a diary helps you to identify the potential triggers of your allergic symptoms by tracking your daily activities, food consumption and general exposure to environmental particulates.

If your symptoms do not improve even after adopting preventive measures or using over-the-counter medications, or if they worsen, contact a healthcare professional for personalized advice.


Allergies can be bothersome and sometimes debilitating. However, with increased awareness of addressing allergies appropriately, living with allergies can be manageable. Understanding the vital role of antihistamines such as chlorpheniramine in managing allergies is crucial for people with these conditions.

At Glovida-Rx, we are committed to providing our customers with personalized advice and reliable access to medications via convenient doorstep delivery. Our pharmacists are delighted to guide you through our extensive selection of antihistamines available on our site to optimize your allergy management.

Visit our website www.glovida-rx.com.sg for more information and feel free to contact us at +65 8101 5555 if you have any queries.


AllergEnd. (n.d.). How to Control and Manage a Dust Mite Allergy. AllergEnd Australia. Retrieved May 23, 2024, from https://www.allergend.com.au/page/how-to-control-and-manage-a-dust-mite-allergy/#:~:text=Wash%20normal%20bed%20sheets%2Flinen
ASCIA. (2024, March). What is allergy? - Australasian Society of Clinical Immunology and Allergy (ASCIA). Www.allergy.org.au. https://www.allergy.org.au/patients/about-allergy/what-is-allergy#:~:text=Allergy%20occurs%20when%20a%20person%27s
Fowler, P. (2016, June 6). What Are Histamines? WebMD; WebMD. https://www.webmd.com/allergies/what-are-histamines
Hogan, L. (2022, November 7). What’s the Difference Between First-Generation and Second-Generation Antihistamines?WebMD. https://www.webmd.com/allergies/difference-between-first-generation-antihistamines-second-generation-antihistamines
Hong, C.-S. (1997). 5th West-Pacific Allergy Symposium: 7th Korea-Japan Joint Allergy Symposium. In Google Books. Monduzzi Editore. https://books.google.com.sg/books/about/5th_West_Pacific_Allergy_Symposium.html?id=3AQjAAAACAAJ&redir_esc=y
Jacqueline A. Pongracic, MD, FAAAAI. (2021). Antihistamines: first generation vs newer antihistamines. Aaaai.org. https://www.aaaai.org/allergist-resources/ask-the-expert/answers/2021/antihistamine
Mayo Clinic. (2018). Allergies - Symptoms and causes. Mayo Clinic. https://www.mayoclinic.org/diseases-conditions/allergies/symptoms-causes/syc-20351497
MedlinePlus. (2017, September 8). MedlinePlus: Histamine: The Stuff Allergies are Made of. Medlineplus.gov. https://medlineplus.gov/medlineplus-videos/histamine-the-stuff-allergies-are-made-of/#:~:text=Histamine%20works%20with%20nerves%20to
MedlinePlus. (2018, July 15). Chlorpheniramine: MedlinePlus Drug Information. Medlineplus.gov. https://medlineplus.gov/druginfo/meds/a682543.html#:~:text=Chlorpheniramine%20helps%20control%20the%20symptoms
MIMS. (n.d.). Chlorphenamine: Indication, Dosage, Side Effect, Precaution | MIMS Singapore. Www.mims.com. https://www.mims.com/singapore/drug/info/chlorphenamine?mtype=generic
Muether, P. S., & Gwaltney, J. M. (2001). Variant Effect of First- and Second-Generation Antihistamines as Clues to Their Mechanism of Action on the Sneeze Reflex in the Common Cold. Clinical Infectious Diseases, 33(9), 1483–1488. https://doi.org/10.1086/322518
Nur Husna, S. M., Tan, H.-T. T., Md Shukri, N., Mohd Ashari, N. S., & Wong, K. K. (2022). Allergic Rhinitis: A Clinical and Pathophysiological Overview. Frontiers in Medicine, 9(9). https://doi.org/10.3389/fmed.2022.874114
O’Sullivan, D. (2023, August 24). Can a HEPA filter vacuum help with allergies and asthma? Asthma Australia. https://asthma.org.au/blog/can-a-hepa-filter-vacuum-help-with-allergies-and-asthma/#:~:text=A%20HEPA%20filter%20vacuum%20cleaner
UpToDate. (n.d.). Chlorpheniramine: Drug information. UpToDate. Retrieved May 23, 2024, from https://www-uptodate-com.libproxy1.nus.edu.sg/contents/chlorpheniramine-drug-information?search=chlorpheniramine&source=panel_search_result&selectedTitle=1%7E72&usage_type=panel&kp_tab=drug_general&display_rank=1#F149972
Wong, Q. Y. A., Lim, J. J., Ng, J. Y., Malipeddi, P., Teo, W. Y., Lim, Y. Y. E., Ng, Y. T., Sio, Y. Y., Matta, S. A., Wong, Y. R., Teh, K. F., Rawanan Shah, S. M., Reginald, K., Say, Y. H., & Chew, F. T. (2022). Allergic rhinitis in Chinese young adults from the Singapore/Malaysia cross-sectional genetics epidemiology study (SMCGES) cohort: Prevalence, patterns, and epidemiology of allergic rhinitis. World Allergy Organization Journal, 15(10), 100704. https://doi.org/10.1016/j.waojou.2022.100704
Back to blog