Two pink boxes, almost the same name: which COLAC were you looking for? Here is the useful difference. Original COLAC contains bisacodyl alone. COLAC II adds DSS to soften hard stool and has an adjustable dose starting at 1 tablet. Both contain a stimulant laxative ingredient, so check the exact name, age and directions together.1,2
I’m Irene, a pharmacist from Taiwan working in Japan.
On this shelf, I would look for the “II” at the end of the name first. Those two strokes change the ingredients and tablet-count instructions. Once you have the right box, the comparison gets much easier.
Similar pink packs, different reasons to choose
ORIGINAL | NO “II”
コーラック
COLAC
Looking for the original, with a labeled use for chronic or habitual constipation
Its only active ingredient is bisacodyl (ビサコジル), which stimulates the large bowel. Taisho positions it for people troubled by recurring constipation. That positioning does not mean you should take it every day long-term.1,3
Adults aged 15 and over: the usual dose is 2 tablets, once daily.1,3,5
II | ADDED DSS, ADJUSTABLE DOSE
コーラックⅡ
COLAC II
Hard stools, or a first-time user wanting to begin at the labeled minimum
Alongside bisacodyl, DSS draws moisture into hard stool to soften it. Taisho also lists first-time laxative users and people wanting to adjust their dose as intended users. Start with 1 tablet, provided the age and pre-use conditions fit.2,4,6
Labeled doses start at age 11. Ages 11–14 and 15+ have different limits, shown below.2,4
“II” does not establish a strength or gentleness ranking. Both contain 5 mg of bisacodyl per tablet; II adds 8 mg of DSS per tablet. These are calculated from the manufacturer’s ingredient totals for 2 original tablets and 3 II tablets, to compare on the same basis. Do not use that comparison to swap tablet counts between products.1,2
If you are shopping from someone’s photo, match the full Japanese name, the presence or absence of II, and the pack size. Pink shades alone are unreliable. The brand has other formulations; this guide’s doses do not apply to the whole COLAC range.
Check the age, tablet count and frequency together
Original COLAC
Ages 15+: usually 2 tablets per dose, once daily.
Take at bedtime or several hours before the expected bowel movement, preferably on an empty stomach.
Do not use original COLAC under age 15. COLAC II’s child dose does not apply to it.1,3,5
COLAC II
| Age | Dose |
|---|---|
| 15 and over | 1–3 tablets |
| 11–14 | 1–2 tablets |
| Under 11 | Do not take |
Start with 1 tablet. Adjust gradually within the labeled range according to bowel movements. Take at bedtime or on an empty stomach; children must be supervised by a parent.2,4
For a readable reference while checking your pack, Taisho provides COLAC English directions (PDF) and COLAC II English directions (PDF). These translations are reading aids; keep the Japanese leaflet supplied with the medicine too.
If I take it at bedtime, when will it work?
For both products, Taisho gives an onset guide of about 6–11 hours after a dose, with individual variation. That helps with planning, but it cannot guarantee a bowel movement before breakfast or a particular train departure.1,2
When travelling, consider whether you can readily reach a toilet, especially before a flight or long bus journey. If COLAC II has not worked after one hour, do not top up. Its manufacturer FAQ says to leave at least a full 24 hours before the next dose.6
For both: water, an empty stomach and whole tablets
- Swallow whole with water or lukewarm water. Do not chew or crush the tablets: their coating is designed for action in the bowel. Remove tablets from the blister first; never swallow the packaging.3,4
- Avoid taking them just after a meal. Original COLAC says preferably on an empty stomach; II says bedtime or an empty stomach. Taisho’s FAQ explains that food can affect the coating.3,4,5
- Leave at least one hour after milk or an antacid before taking a dose. They can make the tablet dissolve in the stomach and affect its intended action. Do not swallow the dose with milk. If using a stomach medicine, check whether it contains an antacid.3,4
Check these situations before choosing a box
Do not combine either product with another laxative or exceed its dose. That also means not taking COLAC and COLAC II together.3,4
Consult a doctor, pharmacist or registered medicine seller before use if you are receiving medical treatment, are pregnant or may be pregnant, or already have severe abdominal pain, nausea or vomiting.3,4
Breastfeeding: check the exact product
Taisho’s FAQ says COLAC and COLAC II can be used while breastfeeding, but stop and contact a doctor if the baby develops unusual loose stools, diarrhea or other changes. If constipation continues for a prolonged period despite treatment, see a doctor and tell them you are breastfeeding. Do not extend this advice to every COLAC formulation.7
When should I stop?
- Severe abdominal pain, nausea or vomiting after taking it: stop immediately and seek advice from a doctor, pharmacist or registered medicine seller, taking the leaflet with you.
- Diarrhea that persists or worsens: stop and seek advice.
- No improvement after about one week: stop and seek advice, rather than adding tablets or combining the two.3,4
Once bowel movements improve, gradually space doses farther apart; II’s dose can also be reduced according to the response. Taisho advises avoiding long-term continuous use of bisacodyl laxatives. Regular meals, fluid intake, activity and time for the toilet also matter; these medicines are not a daily travel-wellness routine.3,4,5
A simple phrase for the drugstore
Show the package photo, then ask:
「コーラックⅡはありますか？」
“Do you have COLAC II?” For the original, ask for 「コーラック」 and confirm that there is no II after the name.
Buying for someone else? Confirm the exact product and the recipient’s age first. If a pre-use consultation condition applies, explain it before choosing. A familiar Japanese brand is not enough to make either medicine suitable as a general gift.
Six questions you may still have
Does the added DSS make COLAC II gentler or pain-free?
You cannot assume that. DSS moistens and softens hard stool, but COLAC II still contains the bowel stimulant bisacodyl. Start with 1 tablet as directed. Stop immediately and seek advice if severe abdominal pain, nausea or vomiting occurs.2,4,6
Can I take more COLAC II if nothing happens after one hour?
Do not take an immediate top-up. The stated onset is about 6–11 hours, with variation between people and with that day’s condition and meals. Taisho’s COLAC II FAQ says to leave at least a full 24 hours before the next dose. Keep to once daily and the age-specific maximum.2,6
Which of these can an 11-year-old take?
COLAC II has a labeled dose for ages 11–14: 1–2 tablets once daily, starting with 1 tablet, under a parent’s supervision. Children under 11 must not take it. Original COLAC is for adults aged 15 and over; do not transfer COLAC II’s child dose to the original.4,5
How long should I wait after milk?
For both products, avoid taking a dose within one hour after milk or an antacid. Leave at least one hour, then swallow the tablets whole with water or lukewarm water. Do not chew or crush them, or use milk to take the dose.3,4
Does “chronic constipation” mean I can take COLAC every day long-term?
Chronic or habitual constipation is the original product’s labeled indication, not permission for ongoing self-treatment. With either product, stop and seek advice if there is no improvement after about one week. Once improved, gradually space doses farther apart; COLAC II’s dose can also be reduced according to bowel movements.1,3,4,5
Can I combine the two, or buy either as a general gift?
Do not combine them or take them with another laxative. When shopping for someone else, confirm the exact product, their age and whether any pre-use consultation condition applies. A pink box alone does not tell you that a medicine is suitable for the recipient.3,4
References and photograph sources
- COLAC catalog and original package photograph
- COLAC II catalog and original package photograph
- COLAC Japanese leaflet: ingredients, directions and warnings
- COLAC II Japanese leaflet: ages, doses and warnings
- COLAC series FAQ: adult age, empty-stomach use and duration
- COLAC II brand page: first-time use, stool softening and repeat-dose interval
- Taisho medicine FAQ: breastfeeding and when to stop
