Histatab — a classic first-generation yellow Chlorpheniramine 4mg allergy tablet
💊 Active ingredient: Chlorpheniramine Maleate ⏱️ How to take: One tablet every 4-6 hours, up to 6 tablets a day 🍽️ Food: With or without food 📦 Pack: 100 tablets per bottle ⚡ Highlight: Fast-acting and low-cost, but causes drowsiness, best taken before bed 🌡️ Storage: Below 30°C, away from light and moisture
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What is Histatab?
Histatab is a Chlorpheniramine 4mg tablet — a classic first-generation antihistamine that eases sneezing, runny nose, itchy nose and eyes, rashes and hives, from both allergies and colds. It works fast, within about 30 minutes, and is very affordable. The main caution is drowsiness, so it is best taken before bed or when itching is severe, and not before driving or operating machinery.
🛒 100 tablets per bottle · 24-hour dispatch from Intimo Life — this medicine causes drowsiness; consult a doctor or pharmacist before use.
Product Description
An antihistamine, Histatab is a Chlorpheniramine 4mg tablet — a classic first-generation antihistamine for allergy symptoms such as sneezing, runny nose, itchy nose and eyes, rashes and hives, from both allergies and colds. Its strengths are fast onset and low cost, though it causes more drowsiness than newer antihistamines.
📊 Key facts
How common is allergic rhinitis — about 400 million people worldwide have it, across all ages (StatPearls — Antihistamines)
Why it makes you drowsy — Chlorpheniramine is a first-generation antihistamine that is fat-soluble and crosses into the brain, causing sedation and anticholinergic effects (StatPearls — Antihistamines)
Standard dose — adults take 4mg every 4-6 hours, not exceeding 24mg per day (StatPearls — Antihistamines)
See other antihistamines that are less sedating in store
🏭 Central Poly Trading (CPL), a Thai manufacturer, makes Histatab using the standard Chlorpheniramine Maleate generic, to the same standard as other chlorpheniramine antihistamines.
⚠️ This medicine causes drowsiness — do not drive or operate machinery after taking it.
Medically reviewed by
Supatcheree A., Pharmacist | Sources: StatPearls, NHS, MedlinePlus
Last reviewed: 2026-07-10
About Histatab
What Is Histatab and How Does It Work?
Histatab is a yellow Chlorpheniramine 4mg antihistamine tablet manufactured by Central Poly Trading (CPL), a Thai pharmaceutical company. It belongs to the first-generation antihistamine class.
It works by blocking H1 histamine receptors, reducing the symptoms triggered when the body releases histamine in response to allergens such as dust, pollen, or pet dander. Chlorpheniramine is a first-generation drug that is fat-soluble and crosses into the brain, so it works quickly but causes drowsiness — unlike newer antihistamines (such as Cetirizine or Loratadine) that are less sedating.
Histatab is the only first-generation chlorpheniramine antihistamine in our lineup. Its advantages are fast onset and low cost, making it well suited to anyone wanting quick relief from itching or allergy symptoms, especially at night.
What Symptoms Does Histatab Treat, and Who Is It For?
Histatab (Chlorpheniramine) relieves a range of allergy symptoms including sneezing, runny nose, itchy nose, itchy and watery eyes from allergic rhinitis, plus rashes, hives and allergic itching. Unlike newer antihistamines, Chlorpheniramine also helps a runny nose from a cold, thanks to its drying (anticholinergic) effect.
It suits people with airborne allergies, rashes or hives who want fast, affordable relief — especially when itching is severe at night, since the drowsy effect can aid sleep.
Anyone who drives, operates machinery, or needs focus during the day should choose a less-sedating newer antihistamine instead, or take Histatab only before bed.
How to Take Histatab Correctly / Recommended Dosage
Dosage: Adults and children aged 12 and over take one tablet (Chlorpheniramine 4mg) every 4-6 hours as needed, up to a maximum of 6 tablets (24mg) per day.
It can be taken with or without food — absorption is not significantly affected. It starts working quickly, within about 30 minutes, and lasts roughly 4-6 hours, so it needs to be taken several times a day — unlike newer once-daily antihistamines.
Because it causes drowsiness, it is best to start with an evening or bedtime dose to test your response, and to avoid alcohol, which increases drowsiness.
What Are the Side Effects of Histatab, and How Common Are They?
The most common side effect of Histatab (Chlorpheniramine) is drowsiness, the hallmark of first-generation antihistamines. Others include dry mouth and throat, blurred vision, difficulty urinating, dizziness and grogginess — the drug's anticholinergic effects.
Because the sedation is pronounced, anyone taking Histatab should not drive, operate machinery, or work at height after a dose, and should avoid alcohol and other sedatives that add to the drowsiness.
For a severe reaction — a widespread rash, swelling of the face or throat, difficulty breathing, or an irregular heartbeat — stop the medicine and seek emergency care immediately.
Contraindications & Precautions for Histatab
Contraindications:
Not for anyone allergic to Chlorpheniramine or any ingredient in the tablet
Not for young children or newborns, and not recommended for children under 12 for this 4mg tablet (a weight-adjusted liquid form should be used instead)
Key precautions:
This medicine causes marked drowsiness — do not drive, operate machinery, or work at height after taking it
Avoid alcohol, sleeping pills and sedatives, which increase the drowsiness
Older adults and people with glaucoma, an enlarged prostate, heart disease, high blood pressure or asthma should consult a doctor or pharmacist before use
How Does Histatab (First-Gen) Compare to Newer Antihistamines in Store?
Histatab uses Chlorpheniramine, a first-generation antihistamine, different from the newer (second- and third-generation) antihistamines in store. All are oral tablets, but differ in speed, price and drowsiness:
Zyrtec (Cetirizine) — second-generation, less sedating, lasts 24 hours, once daily
Telfast (Fexofenadine) — third-generation, the least sedating, good for daytime or before driving
Histatab (Chlorpheniramine) — first-generation, the fastest onset and cheapest, but sedating; best before bed or when itching is severe
Simple guide: Driving or working in the daytime → Telfast, Zyrtec or Aerius | Severe itching needing quick relief, a bedtime dose, or a tight budget → Histatab
How Is Chlorpheniramine Different from Cetirizine?
Chlorpheniramine (the active ingredient in Histatab) is a first-generation antihistamine, while Cetirizine is second-generation. Both block histamine, but differ in three main ways:
Drowsiness — Chlorpheniramine crosses into the brain more, so it is clearly more sedating than Cetirizine
Speed and duration — Chlorpheniramine works faster (about 30 minutes) but lasts a shorter time (4-6 hours, needing repeat doses), while Cetirizine lasts 24 hours and is taken once daily
Price — Chlorpheniramine is the cheapest generic
Choose Chlorpheniramine for fast, low-cost relief you can take before bed; choose Cetirizine for low drowsiness and once-daily dosing.
How Fast Does Histatab Work?
Histatab is one of the fastest-acting antihistamines, easing symptoms within about 30 minutes to an hour of taking it — ideal when you want quick relief from itching, sneezing or a runny nose.
30 minutes - 1 hour — allergy symptoms begin to ease
1-3 hours — blood levels peak for the strongest relief (drowsiness may be most noticeable here)
4-6 hours — the effect starts to fade; you can repeat the dose if symptoms persist, up to 6 tablets a day
Because it is short-acting, it needs several doses a day.
Where Can I Buy Histatab?
Where to Buy Histatab?
Order online at Intimo Life. We deliver across Thailand within 1-3 business days. All orders are packed discreetly, with no product name printed on the outer packaging.
⚠️ Disclaimer
The content in this article is for general educational purposes only. It is not intended to replace professional advice, diagnosis, or treatment from a doctor or pharmacist. If you have any questions about symptoms or medication use, always consult a doctor or pharmacist first.
Always consult a doctor or pharmacist first if pregnant or breastfeeding. Chlorpheniramine has long been used and has a reasonable safety record, but using any medicine in pregnancy should go through individual medical assessment — don't self-medicate.
Histatab causes clear drowsiness, as a first-generation antihistamine. Sleepiness usually appears within 1-2 hours and can last 4-6 hours, and some people feel groggy longer. Take it before bed or when you don't need to drive or concentrate. If you'd rather not feel drowsy, choose a less-sedating newer antihistamine instead.
Yes. Unlike newer antihistamines, Chlorpheniramine has a drying effect, so it also helps a runny nose and sneezing from a cold — not only allergy symptoms. That's why it is often included in combination cold remedies. Be mindful of the drowsiness.
No. Histatab causes drowsiness and reduces concentration, raising the risk of accidents while driving. If you need to drive or stay alert during the day, choose a less-sedating newer antihistamine such as Telfast or Zyrtec instead, and save Histatab for bedtime.
This 4mg tablet is not recommended for children under 12, since the dose must be adjusted by body weight. A Chlorpheniramine liquid (syrup) with a paediatric dose should be used instead. Always consult a doctor or pharmacist before giving antihistamines to a child.
Adults should take no more than 6 tablets (24mg) a day. An overdose can cause severe drowsiness, confusion, palpitations, a fast heartbeat, or seizures, especially in children and older adults. If too much is taken, seek medical care promptly, and never increase the dose yourself.
Taking two antihistamines together isn't recommended, since they work the same way. Combining them doesn't improve effectiveness but increases side effects, especially drowsiness and dry mouth. If symptoms aren't improving on one, consult a doctor or pharmacist.
The active ingredient is the same. Histatab uses standard Chlorpheniramine Maleate 4mg, made by Central Poly Trading. It is affordable because it is a long-established first-generation generic, not because it is weaker. The difference from pricier antihistamines is drowsiness and duration, not quality.
Doctors generally recommend stopping antihistamines for at least 3 to 7 days before an allergy skin test, since the medicine suppresses the skin's reaction and skews results. Tell your doctor or clinic you're taking Histatab for the exact stop period.
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