Japan is a paradise for food lovers. The sushi is extraordinary, the sashimi is fresh, and the seafood culture runs deep. But if you’re visiting from abroad — or even if you’ve lived here for years — there’s one food safety issue worth knowing about: anisakis.
\\n\\n\\n\\nLast updated: March 2026. Medically reviewed by the medical team at SAKURA International Clinic Asakusa.
\\n\\n\\n\\nIt’s not common knowledge among tourists, but anisakis is the most frequently reported foodborne parasite in Japan. Understanding what it is, which foods carry the highest risk, and what to do if symptoms appear can save you a lot of pain — literally.
\\n\\n\\n\\nWhat Is Anisakis?
\\n\\n\\n\\nAnisakis is a parasitic roundworm that lives in the intestines of marine mammals like dolphins and whales. During its larval stage, it infects fish and squid — the same fish and squid that end up on your plate as sushi or sashimi.
\\n\\n\\n\\nWhen a person eats raw or undercooked fish containing live anisakis larvae, the worms can burrow into the stomach or intestinal lining. That’s when the trouble starts.
\\n\\n\\n\\nJapan reports more anisakis cases than any other country in the world. Estimates suggest 7,000 to 8,000 cases per year, though the actual number is likely higher due to underreporting. This isn’t because Japanese food is unsafe — it’s because Japan eats more raw fish than anywhere else. The exposure is simply greater.
\\n\\n\\n\\nThe good news is that anisakis in Japan is well understood, and most cases are treated quickly and effectively. The key is knowing what to watch for.
\\n\\n\\n\\nWhich Fish Are High Risk?
\\n\\n\\n\\nNot all raw fish carry the same level of risk when it comes to anisakis japan cases. Some species are far more commonly involved than others.
\\n\\n\\n\\nHigher-risk fish and seafood include:
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- Mackerel (saba) — The most common culprit. Mackerel is frequently served as sashimi and pickled in vinegar (shime-saba), but vinegar does NOT kill anisakis larvae. \\n
- Squid (ika) — Another high-risk category. Squid can harbor larvae throughout the flesh. \\n
- Salmon (sake/salm) — Wild-caught salmon is a known risk. However, most salmon served at Japanese sushi restaurants is farmed or has been commercially frozen, significantly reducing risk. \\n
- Bonito (katsuo) — Often served lightly seared (tataki), but the interior can remain raw. Carries moderate risk. \\n
- Herring, cod, and yellowtail — Also associated with anisakis cases, though less frequently than the above. \\n
Lower-risk options:
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- Farmed fish — Farmed salmon, sea bream (tai), and yellowtail (hamachi) are raised on controlled diets and rarely carry anisakis. \\n
- Tuna (maguro) — Tuna lives in deep open water and feeds differently from coastal fish. Anisakis infection in tuna is very rare. \\n
- Shrimp, crab, and shellfish — These are not hosts for anisakis and are generally safe from this specific parasite. \\n
This doesn’t mean you need to avoid mackerel or squid entirely. But it’s worth keeping in mind — especially if you’re eating at a small izakaya or a casual fish market stall where fish handling practices may vary.
\\n\\n\\n\\nSymptoms — It Hits Fast and Hard
\\n\\n\\n\\nOne of the most important things to understand about anisakis is that symptoms come on quickly and intensely. This isn’t a slow-building stomach upset. It’s sudden and severe.
\\n\\n\\n\\nTypical symptoms appear within 1 to 12 hours after eating and may include:
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- Severe, cramping pain in the upper abdomen \\n
- Nausea and vomiting \\n
- Bloating and a feeling of fullness or pressure \\n
- In some cases, diarrhea (more common when larvae reach the intestines) \\n
The stomach pain is often described as sharp and persistent — not the kind you can sleep off. Many people assume it’s food poisoning, which makes sense given the timing. But anisakis requires a different type of treatment, so getting the right diagnosis matters.
\\n\\n\\n\\nIf you experience intense stomach pain, vomiting, or severe digestive distress after eating raw fish in Japan, don’t wait it out. See our guide to stomach pain, diarrhea, and vomiting in Japan for more information on what to do and when to seek care.
\\n\\n\\n\\nIntestinal anisakis — where the larvae penetrate the intestinal wall rather than the stomach — is less common but can cause symptoms similar to appendicitis. It may develop more slowly, over 1 to 5 days, and can be harder to diagnose without proper imaging or endoscopy.
\\n\\n\\n\\nTreatment — What the Doctor Will Do
\\n\\n\\n\\nThere is no medication that kills anisakis once it has burrowed into your stomach or intestinal tissue. The primary treatment is endoscopic removal — a doctor uses an endoscope (a thin, flexible camera inserted through your mouth) to locate and physically extract the larva.
\\n\\n\\n\\nThis procedure is very effective. Once the larva is removed, symptoms typically resolve quickly — often within hours. Japan’s gastroenterology departments are experienced with this, so endoscopic removal is usually done efficiently and without major complications.
\\n\\n\\n\\nWhat to expect at the clinic or hospital:
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- A doctor will take your history and ask about what you ate and when \\n
- Diagnosis is usually confirmed with endoscopy or, in some cases, imaging \\n
- If found in the stomach, endoscopic removal is performed on the spot \\n
- If larvae have reached the intestines, treatment may involve observation, anti-inflammatory medication, and in rare cases, surgery \\n
Some people have an allergic reaction to anisakis rather than — or in addition to — the classic mechanical symptoms. In allergic-type anisakis, the immune system reacts to proteins in the parasite, causing hives, swelling, or more serious allergic responses. This type can sometimes occur even with cooked fish if the proteins remain intact.
\\n\\n\\n\\nIf you develop abdominal pain alongside skin reactions like hives or significant swelling, make sure to mention both to the doctor. The treatment approach may differ.
\\n\\n\\n\\nHow to Enjoy Sushi Safely in Japan
\\n\\n\\n\\nPlease don’t let this information put you off sushi. Japan’s raw fish culture is one of the most refined in the world, and the vast majority of people eat it without any problems. With a few simple habits, you can significantly reduce your risk while still enjoying everything Japan’s food scene has to offer.
\\n\\n\\n\\n1. Choose reputable restaurants
\\n\\n\\n\\nQuality sushi restaurants and established fish markets take hygiene seriously. High-end sushi counters, major conveyor belt chains, and licensed seafood restaurants typically follow strict handling and storage standards. Street stalls or informal settings with uncertain refrigeration are higher risk.
\\n\\n\\n\\n2. Understand the role of freezing
\\n\\n\\n\\nFreezing is the most effective way to kill anisakis larvae. The Japanese Food Sanitation Law recommends freezing fish at −20°C for 24 hours or more before serving raw. Most commercial sushi operations and supermarkets follow this standard. However, very fresh “live catch” fish served the same day — which is considered a premium in Japan — may not have been frozen.
\\n\\n\\n\\nIf you’re concerned, it’s completely acceptable to ask staff whether the fish has been frozen. This is a normal question, especially in the context of raw fish safety.
\\n\\n\\n\\n3. Fully cooking fish eliminates the risk
\\n\\n\\n\\nHeat above 60°C kills anisakis. If you’re immunocompromised, pregnant, or simply prefer to err on the side of caution, choosing grilled, baked, or hot-pot fish dishes removes this risk entirely.
\\n\\n\\n\\n4. Chew thoroughly
\\n\\n\\n\\nThorough chewing can physically destroy larvae before they cause harm. This won’t eliminate all risk, but it does help. The Japanese concept of chewing food well is practical advice here — and not just for digestion.
\\n\\n\\n\\n5. Note: vinegar and salt do not kill anisakis
\\n\\n\\n\\nA common misconception is that vinegar-marinated fish (like shime-saba) or salted preparations are safe. They are not. Anisakis larvae can survive both acidic and salty environments. Only heat and deep freezing are reliable.
\\n\\n\\n\\nAnisakis Allergy — A Growing Concern
\\n\\n\\n\\nBeyond the classic “worm burrowing into your stomach” scenario, there’s a separate and increasingly recognized condition: anisakis allergy.
\\n\\n\\n\\nIn this case, the body develops an immune sensitivity to anisakis proteins. Once sensitized, a person may experience allergic reactions every time they eat fish — even fully cooked fish — because the proteins can survive cooking even when the larvae are dead.
\\n\\n\\n\\nSymptoms of anisakis allergy can include:
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- Hives (urticaria) or widespread skin itching \\n
- Swelling of the face, lips, or throat \\n
- Wheezing or difficulty breathing \\n
- Anaphylaxis in severe cases — a potentially life-threatening reaction requiring emergency treatment \\n
Anisakis allergy is more common in countries with high raw fish consumption — making Japan one of the most affected populations. It can develop after a single anisakis infection or after repeated low-level exposures over time.
\\n\\n\\n\\nIf you’ve had an anisakis infection in the past and later notice allergic reactions after eating seafood, this could be the reason. Similarly, if you develop hives or swelling after eating fish in Japan without an obvious prior infection, it’s worth discussing with a doctor.
\\n\\n\\n\\nFor more information about allergic reactions and skin symptoms while in Japan, see our guide to allergies, rash, and itching.
\\n\\n\\n\\nDiagnosis of anisakis allergy is made through blood testing (specific IgE antibodies). Management involves avoiding raw fish and, in some cases, being prescribed an epinephrine auto-injector for emergency use.
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Related Pages
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- Stomach Pain, Diarrhea & Vomiting in Japan — What to Do \\n
- Allergies, Rash & Itching in Japan — English Clinic Guide \\n
- Food Safety in Japan for Tourists — What You Need to Know \\n\\n
- Norovirus in Japan: Winter Stomach Bug \\n
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Frequently Asked Questions
\\n\\n\\n\\nWhat is anisakis and how do you get it?
\\n\\n\\n\\nAnisakis is a parasitic roundworm found in raw or undercooked seafood, particularly mackerel, squid, salmon, and sardines. Japan reports over 7,000 cases annually—the highest worldwide. Infection occurs when live larvae in raw fish are swallowed and burrow into the stomach lining.
\\n\\n\\n\\nWhat are the symptoms of anisakis infection?
\\n\\n\\n\\nSevere stomach pain, nausea, and vomiting typically begin 2–8 hours after eating contaminated raw fish. The pain is often sharp and cramping. Some patients develop allergic reactions including hives or anaphylaxis. Symptoms can mimic appendicitis or food poisoning.
\\n\\n\\n\\nHow is anisakis treated in Japan?
\\n\\n\\n\\nTreatment involves endoscopic removal of the worm from the stomach lining, providing immediate pain relief. This costs approximately ¥15,000–30,000 without insurance. Japanese gastroenterologists are highly experienced with anisakis cases. Emergency rooms in major cities can usually perform the procedure same-day.
\\n\\n\\n\\nIs sushi safe to eat in Japan?
\\n\\n\\n\\nYes, sushi at reputable restaurants is very safe. Professional sushi chefs are trained to detect and remove anisakis larvae. High-end establishments use careful visual inspection and proper preparation techniques. The highest risk comes from homemade sashimi or lesser-quality raw fish.
\\n\\n\\n\\nDoes freezing kill anisakis?
\\n\\n\\n\\nYes. Freezing fish at -20°C for 24 hours or longer kills anisakis larvae. The EU and US require commercial freezing of fish sold raw, but Japan does not mandate this. Many Japanese restaurants serve truly fresh, never-frozen fish, relying instead on visual inspection by trained chefs.
\\n\\n\\n\\nNeed Help? We’re Here for You.
\\n\\n\\nSAKURA International Clinic Asakusa is open every day, 9:00–17:00, just one minute from Asakusa Station. Walk-ins welcome. All consultations in English.
\\n\\n\\n\\n\\n\\nComprehensive consultation: ¥55,000 (includes exam, prescription, basic tests, and medical certificate if needed).
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