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🏥 Gotokuji Orthopedic Clinic / Patient Guide

Acetaminophen (Calonal) Guide

Calonal / Tylenol
A pain reliever that is relatively easy on the stomach - how to use it properly

Calonal (acetaminophen) is a pain reliever and fever reducer that is relatively easy on the stomach.
It works by acting on the central nervous system in the brain to lower your sense of pain, which is different from how loxoprofen (Loxonin) works.
It is easy to use for elderly patients, people with sensitive stomachs, pregnant women, and children (if you are pregnant, do not decide on your own - always consult your doctor first).
However, it has weak anti-inflammatory effects, so loxoprofen may be better for pain with swelling. It must not be used if you have a peptic ulcer, severe liver or kidney problems, or aspirin-induced asthma.

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Works in the brain to reduce pain signals

Instead of reducing inflammation at the injury site, it weakens pain signals in the brain

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Relatively easy on the stomach

It affects the stomach lining less than loxoprofen does, but the risk is not zero

3
Works gently

Takes effect in 1-2 hours and lasts 4-6 hours

4
Watch out for overdose

Taking more than the daily limit can cause liver damage

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Reducing fever
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Headache and sore throat
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Mild to moderate pain of any kind
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Long-term management of chronic pain
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Pain management for elderly patients, those with sensitive stomachs, or reduced kidney function
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Single Dose
500-1000 mg (adjusted by your doctor based on weight and symptoms)
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Dosing Interval
Wait at least 4-6 hours between doses
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Daily Maximum
Up to 4000 mg total per day (the package insert limit; follow your doctor's instructions for your actual dose). For OTC products, always follow the dosage printed on the package
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When to Take
The Japanese package insert advises avoiding doses on an empty stomach - take it after a meal whenever possible
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Avoid Alcohol
Combining with alcohol greatly increases the burden on your liver
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Watch for Double-Dosing
Many cold medicines also contain acetaminophen - check labels carefully
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A relatively low burden, suitable for a wide range of patients

Compared with NSAIDs, acetaminophen has relatively less effect on the stomach, kidneys, and cardiovascular system, making it easy to prescribe for elderly patients and those with other health conditions. However, its anti-inflammatory effect is weaker than loxoprofen, so loxoprofen works better for strong swelling and inflammation. Stay within the daily dose limit and use it safely.

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The biggest risk of acetaminophen is liver damage from overdose.
Taking more than the daily limit or taking it right after drinking alcohol can cause nausea, fatigue, and jaundice (yellowing of the skin). Many cold medicines and multi-symptom OTC drugs also contain acetaminophen, so be careful not to accidentally double up. If you develop strong symptoms, see a doctor right away.

💡 4 Rules for Safe Use

  • Stay within the daily limit (4000 mg total per day). If you take more than 1500 mg a day over a long period, your liver function needs to be checked regularly
  • Taking it after drinking, on an empty stomach, or while fasting puts extra stress on the liver
  • Watch out for overlap with other medicines containing acetaminophen
  • If nausea or fatigue continues, stop taking it and see your doctor promptly