The three Colgen Kowa IB boxes contain different combination cold medicines. TXα is taken as three tablets three times daily; Clear Capsules α Plus as two capsules three times daily; IB2 as two sustained-release capsules twice daily. They all have a minimum age of 15, can cause drowsiness and must not be combined.
I'm Irene, a Taiwan-born pharmacist licensed in Japan and working in a Japanese drugstore. I'll help you compare the complete names, daily ingredient amounts and easily missed safety differences before choosing a Colgen box.
Sources checked: 13 October 2026. These are three selected Japanese-market designated Class 2 OTC medicines, not the whole Colgen range. The latest Japanese leaflets linked by Kowa control this comparison; read the leaflet in your pack before use.
- First: is a combination cold medicine suitable?
- Three names to recognise on the shelf
- Doses: three times daily or twice daily?
- Compare ingredients on the same daily basis
- What the dosage forms look like
- Which combinations and medical conditions matter?
- Stop points are counted in doses, not days
- Buying in Japan: expect safety questions
- Official sources and image credits
First: is a combination cold medicine suitable?
All three are labelled to relieve cold symptoms, including sore throat, fever, chills, headache, cough, phlegm, runny or blocked nose, sneezing, joint pain and muscle pain. They do not diagnose what is causing those symptoms. A single symptom does not automatically require a multi-ingredient product; let a pharmacist check what treatment, if any, is needed.
Do not take any of these three if you are under 15, have had an allergic reaction to that product or its ingredients, have had asthma after taking a cold medicine or a pain/fever medicine, or are within 12 weeks of your expected delivery date. Pregnancy or possible pregnancy at other stages still requires advice before use.
For all three: do not drive or operate machinery after taking them; do not drink alcohol before or after use; do not use for more than five days; and never exceed the labelled dose. IB2 also warns about blurred vision and unusual sensitivity to brightness. Caffeine in the formulas does not cancel these driving restrictions.
Three names to recognise on the shelf
| Product | Package wording to match | Main formulation difference |
|---|---|---|
| Colgen Kowa IB Tablets TXα | コルゲンコーワIB錠TXα | Contains tranexamic acid as well as ibuprofen and ambroxol |
| Colgen Kowa IB Clear Capsules α Plus | コルゲンコーワIB透明カプセルαプラス | Liquid-filled soft capsules; no tranexamic acid |
| Colgen Kowa IB2 | コルゲンコーワIB2 | Sustained-release capsules; isopropamide and dextromethorphan; twice daily |
Doses: three times daily or twice daily?
The following doses apply only to ages 15 and over. All three are prohibited under 15. Take with water or warm water, preferably within 30 minutes after the specified meals.
| Product, ages 15 and over | Amount per dose | Frequency and meal timing | Total in one labelled day |
|---|---|---|---|
| TXα tablets | 3 tablets | 3 times daily after meals | 9 tablets |
| Clear Capsules α Plus | 2 capsules | 3 times daily after meals | 6 capsules |
| IB2 | 2 capsules | 2 times daily, after breakfast and dinner | 4 capsules |
IB2's different release system is why its schedule is twice daily. Do not add a lunchtime dose or replace it with a dose of another cold medicine. Two capsules can mean a different formula and daily schedule depending on which box you have.
Compare ingredients on the same daily basis
All amounts below are per full labelled day for ages 15 and over: TXα 9 tablets, Clear Capsules α Plus 6 capsules, or IB2 4 capsules. IB2's leaflet prints its ingredients per two-capsule dose; those amounts have been multiplied by two here for a like-for-like daily comparison. A dash means the ingredient is not in that product's active-ingredient list.
| Active ingredient | TXα: per day | Clear Capsules α Plus: per day | IB2: per day |
|---|---|---|---|
| Ibuprofen | 600 mg | 600 mg | 400 mg |
| Tranexamic acid | 750 mg | — | — |
| Ambroxol hydrochloride | 45 mg | 45 mg | — |
| d-Chlorpheniramine maleate | 3.5 mg | 3.5 mg | 3.5 mg |
| Dihydrocodeine phosphate | 24 mg | 24 mg | — |
| dl-Methylephedrine hydrochloride | 60 mg | 60 mg | 60 mg |
| Anhydrous caffeine | 75 mg | 40 mg | 75 mg |
| Isopropamide iodide | — | — | 5 mg |
| Dextromethorphan hydrobromide hydrate | — | — | 48 mg |
All three supply ibuprofen 200 mg per dose, but IB2 is taken fewer times per day. TXα adds tranexamic acid; TXα and the clear capsules include the phlegm-loosening ingredient ambroxol and the cough suppressant dihydrocodeine. IB2 instead has dextromethorphan for cough and isopropamide to reduce nasal secretions. Neither a larger daily milligram figure nor liquid-filled packaging establishes that one product is the best choice for everyone.
What the dosage forms look like
Which combinations and medical conditions matter?
Do not combine any of these with another cold medicine, pain/fever medicine, sedative, cough/phlegm medicine, or oral medicine containing an antihistamine, including many rhinitis, motion-sickness and allergy products. Check everything you already took that day with a pharmacist; different brand names do not prevent ingredient overlap.
- TXα also prohibits other oral medicines containing tranexamic acid, which can appear in throat medicines and other products.
- IB2 also prohibits gastrointestinal pain-relieving/antispasmodic medicines. Show the actual stomach-medicine pack to the pharmacist rather than assuming all stomach medicines are alike.
- TXα and Clear Capsules α Plus must not be used while you are receiving medical treatment for stomach/duodenal ulcers, blood disease, liver disease, kidney disease, heart disease or high blood pressure, or are taking zidovudine. IB2 handles several of these conditions under pre-use consultation; that difference does not establish that it is suitable for you.
For all three, get advice before use if you are receiving medical or dental treatment, are older, have a medicine-allergy history, high fever or difficulty urinating. The leaflets also list conditions needing review, including thyroid dysfunction, diabetes, glaucoma, systemic lupus erythematosus, mixed connective tissue disease, and past stomach/duodenal ulcer, ulcerative colitis or Crohn's disease. Give the pharmacist your full diagnosis and medicine list rather than checking only the conditions mentioned here.
TXα additionally requires consultation for a blood clot or a risk of clotting. TXα and Clear Capsules α Plus specifically list bronchial asthma, impaired breathing, obstructive sleep apnoea and obesity, as well as past blood, liver or kidney disease. IB2 specifically lists diagnosed heart disease, high blood pressure, liver disease and kidney disease. Read each complete leaflet; the consultation lists are not interchangeable.
Breastfeeding instructions also differ. TXα and Clear Capsules α Plus say either do not take the medicine or avoid breastfeeding while taking it. Ask a clinician or pharmacist for a suitable plan rather than stopping breastfeeding on your own. IB2 lists breastfeeding under consultation before use; it is not an automatic breastfeeding-safe alternative.
For ingredient allergies or other ingredient restrictions, check the inactive ingredients too. TXα lists lactose; Clear Capsules α Plus lists gelatin and soy lecithin; IB2 lists gelatin. These examples are not complete allergen lists.
Stop points are counted in doses, not days
| Product | Stop and consult if symptoms do not improve after… |
|---|---|
| TXα tablets | 5–6 doses |
| Clear Capsules α Plus | 5–6 doses |
| IB2 | 3–4 doses |
All three highlight fever that lasts three days or more, or repeatedly returns, as a reason to stop and consult. All prohibit use for more than five days. These are separate limits, not permission to keep taking the medicine until day five if the earlier stop point is reached or symptoms worsen.
Stop immediately and seek advice for possible adverse effects such as a rash, stomach pain, palpitations, difficulty urinating, unusual bleeding or marked weakness. Persistent or worsening dry mouth, constipation or drowsiness also calls for stopping and consultation. Breathing difficulty, a severe allergic reaction, a widespread rash with high fever or sore eyes/lips, vomiting blood or black stools, chest pain, or sudden one-sided weakness or speech difficulty require urgent medical care. These examples do not replace the full leaflet's adverse-effect list.
Buying in Japan: expect safety questions
Kowa lists all three under Japan's designated misuse-prevention medicine system introduced on 1 May 2026. The seller must make safety checks, including age, other medicines and purchases of these medicines elsewhere; larger or multiple-pack purchases require additional checks. Answer honestly and buy only an appropriate amount. Kowa says package changes are being introduced gradually, so an older-looking box may not display the newer checking mark. The sales check is separate from the medicine's age-15 dosing limit.
Keep the original box and leaflet. Store the blisters away from heat, direct sunlight and humidity, out of children's reach; do not transfer the medicine to another container or use it after expiry. Protect the blister foil and remove each tablet or capsule from it before swallowing.
The shortest useful comparison is: confirm suitability, match the full product name, check the other medicines already taken, then follow that exact dose and stop point. A request for “the Colgen cold medicine” needs a photograph or the full variant name before you buy it.
Official sources and image credits
- Kowa: IB Tablets TXα product information and current Japanese leaflet.
- Kowa: IB Clear Capsules α Plus product information and current Japanese leaflet.
- Kowa: IB2 product information and current Japanese leaflet.
- Kowa: May 2026 package and misuse-prevention notice.
- Japan's Ministry of Health, Labour and Welfare: sales requirements for designated misuse-prevention medicines.
- Package, blister and capsule photographs: Kowa, from the linked current product pages.
