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Allergic Reaction in Japan: What to do (hives, swelling, trouble breathing)

Last updated: 2026-03-03

TL;DR (30-second decision)

  • Call 119 now if you have trouble breathing, throat tightness, swelling of lips/tongue/face, wheezing, fainting, or you feel your reaction is getting worse fast. This can be anaphylaxis and is an emergency.
  • If you have an epinephrine auto-injector (EpiPen®), use it immediately for severe symptoms, then call 119 even if you feel better afterward.
  • Mild symptoms (local itching / a few hives, no breathing symptoms): you may try OTC antihistamines and monitor closely—but escalate quickly if symptoms spread or breathing/swallowing changes.

(This page is general guidance, not medical diagnosis.)

Call 119 immediately (red flags = possible anaphylaxis)

Call 119 right away if any of the following happen after eating, medication, insect stings, or unknown triggers:

  • Trouble breathing, wheezing, persistent cough, or “can’t get air”
  • Throat tightness, hoarse voice, difficulty swallowing
  • Swelling of lips, tongue, face, or throat
  • Dizziness, fainting, confusion, collapse
  • Rapidly spreading hives with any breathing/circulation symptoms

Tokyo’s emergency guidance for food allergy reactions explicitly says to call an ambulance (119).

What to do right now (safe steps)

1) Stop exposure

  • Stop the suspected food/medicine immediately.

2) If you have an EpiPen®

  • Use it for severe symptoms, then call 119. Even if symptoms improve, further medical treatment may be needed.

3) If symptoms are mild (no breathing/swallowing issues)

  • Stay with someone (don’t be alone).
  • Monitor for progression for at least a few hours.
  • Consider OTC allergy medicine (see below).

4) If symptoms are worsening

  • Don’t “wait and see.” Escalate to 119.

Allergy vs. food poisoning (quick distinction)

These can look similar after eating, but the danger level is different.

More suggestive of allergy

  • Hives, itching, flushing
  • Swelling (lips/face/tongue)
  • Breathing symptoms or throat tightness
  • Often starts within minutes to 1–2 hours

More suggestive of food poisoning

  • Mainly vomiting/diarrhea/cramps
  • Often starts hours later
  • May affect multiple people who ate the same food

If hives/swelling/breathing symptoms appear → treat as allergy emergency (119).

OTC options in Japan (mild symptoms only)

For mild symptoms (itching, runny nose, mild hives without red flags), drugstores commonly carry:

  • Oral antihistamines (non-drowsy and drowsy types)
  • Anti-itch creams or steroid creams (for localized itching)
  • Eye drops / nasal sprays (for seasonal allergies)

Important: If you have red flags, do not rely on OTC meds—call 119.

Japan-specific: food allergy labeling + communication tools

In Japan, food labeling rules specify 28 allergen items that must/can be declared (depending on category).
Tokyo also provides a Food Allergy Communication Sheet you can print and show at restaurants—useful for travelers.

(This doesn’t guarantee safety, but it reduces misunderstandings.)

“Why did this happen now?”

Poor sleep and circadian disruption can worsen inflammatory symptoms and make you feel more reactive or miserable (and allergy symptoms can also worsen sleep—vicious cycle).
If you’re traveling, use your Jet lag and Sleepless pages to stabilize sleep and reduce symptom spirals.

What to say (simple English)

Calling 119

“I think I’m having an allergic reaction.”
“I have trouble breathing / my throat feels tight / my lips are swelling.”
“My location is [hotel / station / landmark]. Please send an ambulance.”

(119 connects to the fire department dispatch system; they handle ambulance calls. )

At a pharmacy (mild symptoms)

“I have an allergic reaction (hives/itching). No breathing problems.”
“I want a non-drowsy antihistamine, if possible.”
“I’m taking [other medicines] / I have [asthma/ulcer/kidney disease].”

At a restaurant (prevention)

“I have a serious food allergy to [peanuts / shellfish / egg].”
“Can you confirm if this contains [allergen]?”
(Use a printed communication sheet if available. )

FAQ

What is anaphylaxis?

Anaphylaxis is a severe allergic reaction that can affect breathing and circulation and can become life-threatening quickly. If you suspect it, call 119.

If I used an EpiPen®, do I still need to call an ambulance?

Yes. Guidance states to use epinephrine and call an ambulance as soon as possible, because further treatment may be needed even if you improve.

Is “hives only” an emergency?

Not always—but it can progress. If hives spread rapidly or you develop swelling, throat tightness, wheezing, dizziness, or faintness, treat it as urgent and call 119.

How can I reduce risk when eating out in Japan?

Use allergen labeling, ask direct questions, and consider using a printed Food Allergy Communication Sheet.

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