"Summer Thrombosis" - A "Hidden Killer" Easily Mistaken for Heatstroke: A Risk and Countermeasure Guide for Foreign Residents

Table of Contents

1. Introduction – Why "Summer Thrombosis" is a Threat to Foreigners

2. What is "Summer Thrombosis"?

3. Comparison Table with Heatstroke

4. "Critical Time Zone" and Early Week Risks

5. Case Study: Experience of a 51-Year-Old Man

6. High-Risk Groups and Lifestyle Factors

7. 10 Immediate Preventive Measures

8. Key Points for Receiving Emergency Medical Care in Japan

9. Frequently Asked Q&A

10. Conclusion – "Hydration + Early Morning Care" is the Key to Saving Lives

11. List of Reference Articles

1. Introduction – Why "Summer Thrombosis" is a Threat to Foreigners

Japan's summer is characterized by "muggy heat" with temperatures around 35 °C and humidity above 70%. People from Europe, America, and the Middle East, who are accustomed to dry heat, tend to have difficulty regulating body temperature, leading to rapid dehydration. Dehydration increases blood viscosity, which is a significant factor in thrombus formation.doctorbook.jp

2. What is "Summer Thrombosis"?

• Definition: A phenomenon where thrombosis forms under dehydration and high-temperature stress in midsummer, blocking arteries in the brain, heart, and lungs.

• Mechanism: Dehydration→blood concentration→platelet aggregation↑+fibrinolytic activity↓→thrombosis formation. Virchow's triad (stasis of blood flow, endothelial injury, changes in blood composition) worsens simultaneously.doctorbook.jp

• Main Diseases: Cerebral infarction, myocardial infarction, pulmonary embolism, deep vein thrombosis.

3. Comparison Table with Heatstroke

4. "Critical Time Zone" and Early Week Risks

• Time Zone: 1 to 4 hours after waking up (approximately 6–10 am) is the "critical time zone" where a sharp rise in blood pressure and a decrease in fibrinolytic activity coincide.mezamashi.mediadiamond.jp
  
  

• Day of the Week: On Mondays, stress hormones increase due to disrupted sleep rhythms and alcohol consumption over the weekend, increasing thrombotic tendencies.mezamashi.media

5. Case Study: Experience of a 51-Year-Old Man

Last summer, Mr. Hosokawa (51), residing in Saitama Prefecture, mistook his fatigue for "mild dehydration" and went to bed. When he got up to use the bathroom at dawn, he experienced paralysis on his right side and fell. He was rescued by his mother's call, but he reflects, "If I had lived alone, I might have died alone." The emergency doctor explained, "If we had arrived 30 minutes later, paralysis would have remained or he would have died."news.ksb.co.jp

6. High-Risk Groups and Lifestyle Factors

• Underlying Conditions: Hypertension, diabetes, dyslipidemia, obesity.

• Behavioral Factors: Long flights, sitting for long periods during remote work, excessive alcohol and caffeine intake, dehydration after sauna use.doctorbook.jpkashijoumyakuryuu.jp

7. 10 Immediate Preventive Measures

1. Drink at least one glass (200 mL) of water at room temperature immediately after waking up.
   
   

2. During the day, be mindful of "sweat volume ≒ water + electrolyte intake" (sports drinks or oral rehydration solutions).
   
   

3. Keep room temperature below 28 °C and humidity below 60% even in early morning and night (recommended automatic air conditioner operation).
   
   

4. Limit alcohol before bed to one medium bottle of beer and drink at least the same amount of water.
   
   

5. Stand up and stretch your calves every hour.
   
   

6. Use elastic stockings or compression socks (during airplane or bullet train travel).
   
   

7. Avoid high-intensity training on Monday mornings.
   
   

8. Take prescribed medications (anticoagulants, antihypertensives) as directed by your doctor.
   
   

9. If you suspect symptoms, use the "FAST" assessment: Face, Arm, Speech, Time. Call 119 if any one item applies.
   
   

10. Share a monitoring app with family and friends to detect abnormalities early.news.ksb.co.jp

8. Key Points for Receiving Emergency Medical Care in Japan

• 119 Call Phrase (in Japanese)

  "There is a suspicion of a stroke. Please provide an English-speaking doctor."

• English-Speaking Hospital Search: Japan National Tourism Organization (JNTO) "Guide to Medical Facilities."

• Payment: Present your passport and overseas travel insurance certificate. Confirm cashless payment availability in advance.

• Interpreter at the Hospital: Use telephone medical interpretation services (such as AMDA Medical Information Center).

9. Frequently Asked Q&A

Q1: Can I drink tea or coffee instead of water?
A: Caffeine has a diuretic effect that can promote dehydration, so water or low-concentration electrolyte drinks are safer.

Q2: Is it better not to soak in the bath and just take a shower at night?
A: Prolonged hot baths can actually worsen dehydration. A short bath at about 38 °C is better.

Q3: I've heard wine is good for preventing thrombosis?
A: While polyphenols have beneficial effects, excessive drinking is counterproductive. Moderate consumption (one glass) plus hydration is essential.

10. Conclusion – "Hydration + Early Morning Care" is the Key to Saving Lives

Summer thrombosis is a "silent killer" that can disguise itself as heatstroke and threaten life in a short time. Especially important is managing hydration and blood pressure between 6 and 10 am. A glass of water, proper air conditioning, and if you feel any abnormalities, do not hesitate to call 119. To prevent delays due to language barriers, foreign residents in Japan should register the contact information for medical interpretation services on their smartphones.

List of Reference Articles

• KSB Seto Inland Sea Broadcasting "Doctors Warn of 'Summer Thrombosis' with Symptoms Similar to Heatstroke Amidst a Surge in Hot Days" (June 29, 2025)##HTML_TAG_