Foodborne botulism symptoms usually begin 18–36 hours after exposure, but onset can range from about 6 hours to 10 days.
Early Start
Typical Start
Prolonged
Food Route
- Pressure can low-acid jars
- Boil jars 10 minutes before serving
- Discard bulging or spurting cans
Low-acid jars
Wound Route
- Clean and cover deep injuries
- Seek care for injection wounds
- Antitoxin via hospital only
4–14 days
Infant Route
- No honey under 12 months
- Watch constipation + weakness
- Hospital evaluation early
BabyBIG eligible
When Botulism Signs Appear: Typical Timelines
Most adults who swallow the toxin through food develop early stomach upset or nothing at all, then neurologic changes. The common window is 18–36 hours after the meal. Reported ranges stretch from about 6 hours to 10 days because dose, food matrix, and gut transit vary from person to person.
The picture shifts by route. With a contaminated wound, nerves may falter several days after injury—often between 4 and 14 days. In babies, spores can settle in the gut and make toxin there, so signs build gradually across days, not hours.
Early Clues That Matter
Watch for double or blurred vision, droopy eyelids, trouble speaking, dry mouth, and trouble swallowing. Nausea, vomiting, or cramping can show up first with food sources, then the neurologic pattern sets in: weakness that starts in the face and moves downward. Breathing can slip as the diaphragm weakens. Call for urgent care if face or throat weakness, short breath, or spreading weakness appears.
Onset Ranges By Exposure Type
The table below distills typical timing and helpful notes across the main forms seen in kitchens and clinics.
| Type | Usual Start | Range & Notes |
|---|---|---|
| Foodborne | 18–36 hours | From ~6 hours to 10 days; early GI upset possible |
| Wound | 7 days | About 4–14 days after injury; injection wounds common |
| Infant | Days to weeks | Constipation first; honey is a known risk for babies |
| Adult intestinal | Days | Rare colonization in gut after surgery, antibiotics, or bowel disease |
| Iatrogenic | Hours to days | After botulinum toxin procedures if dose spreads |
If you home-can vegetables or meat, follow pressure canning rules for low-acid foods. Water-bath methods can’t reach temperatures that disable spores. Electric multi-cookers with “canning” buttons aren’t approved for low-acid jars. Official guidance stresses pressure equipment built for canning; see the CDC’s page on home-canned foods for clear steps.
Dense kitchen topics pair well with step-by-step refreshers. When you’re getting jars ready, a refresher on canning safety for beginners keeps the process safer without slowing you down.
Why Timelines Vary So Much
Dose matters. More toxin tends to mean a faster start. Food texture and fat content can slow absorption. Protective packaging, like foil around baked potatoes, can also set up a low-oxygen pocket during cooling that favors growth before serving. The body’s own factors shape the course too: gut motility, stomach acid, and the health of nerves that control the face and throat.
How Each Route Works
Swallowed Toxin From Food
In home kitchens, risk spikes with low-acid jars that weren’t pressure canned, garlic in oil left at room temp, and buried leftovers that sat for days. People often start with dry mouth or trouble focusing, then notice a softening voice or droopy lids. Weakness tends to descend from head to toe. CDC clinical guidance describes this cranial-nerve pattern in detail; see the clinical guidelines for the overview and treatment steps.
Toxin Made Inside A Wound
Soil can seed a deep cut. Injection drug use also creates low-oxygen tissue where the bacteria make toxin. Because the toxin is produced inside the body, the gap between exposure and signs stretches out to several days. The same cranial-nerve pattern shows up: slurred speech, facial weakness, and trouble swallowing.
Colonization In Babies
Babies don’t have mature gut defenses yet. Spores can germinate and make toxin in the colon, so the timeline is slower and steadier. Constipation, weak cry, poor feeding, and floppiness are common. Never give honey under 12 months; the CDC’s infant overview lists the classic signs.
Red Flags That Call For Immediate Care
Call an ambulance if any of these appear after a risky meal, a deep wound, or in a baby who has new constipation with weakness:
- Face weakness, droopy eyelids, double vision, or slurred speech
- Trouble swallowing saliva or liquids
- Short breath, shallow breathing, or tiring while talking
- In babies: floppiness, weak cry, poor suck, or blue spells
Clinicians confirm the pattern by exam and may send stool, serum, or food for toxin testing. Treatment is antitoxin given in the hospital, plus close breathing support as needed. Babies receive a specific product. People with wound disease need care for the injury as well.
Care Timeline: What Happens After You Seek Help
In the emergency department, staff check the airway, breathing, and oxygen levels. If weakness points to botulism, the team contacts public health to release antitoxin. The sooner this is given, the more nerve endings are protected from further paralysis. Nerves blocked by toxin need time to regenerate, so recovery can take weeks. Physical therapy and nutrition support help the process.
What Antitoxin Does—And Doesn’t
Antitoxin neutralizes toxin that hasn’t bound to nerves yet. It doesn’t reverse paralysis that already set in. That’s why timing is central. With infant cases, a specialized immune product is used. For wounds, surgery and antibiotics may be part of the plan.
Kitchen Moves That Lower Risk
Most home cooks can keep risk low with a handful of habits. Use pressure canning for low-acid foods. Keep oil-packed garlic and herbs in the fridge and finish them within the recommended window. Boil homemade low-acid jars for 10 minutes before serving. Toss bulging, leaking, or off-smelling cans. When baking potatoes in foil for a party, hold them hot or move them to the fridge within two hours.
Parents and caregivers can help babies stay safe by skipping honey during the first year. Watch diapers and feeding. If stool patterns change and weakness shows up, get care fast. The CDC’s infant overview lists hallmark signs you can share with your pediatric team.
Home Prevention Checklist
| Risky Practice | Safer Move | Extra Note |
|---|---|---|
| Water-bath canning low-acid jars | Use a pressure canner | Targets spores in beans, meat, and veggies |
| Room-temp garlic or herb oil | Refrigerate and date | Finish within a short window |
| Foil-wrapped potatoes cooling on the counter | Hold hot ≥ 60℃ / 140℉ or chill | Low oxygen under foil fosters growth |
| Feeding honey to babies | Wait until after 12 months | Stick with pasteurized foods made for infants |
| Ignoring bulging or spurting cans | Discard without tasting | When in doubt, throw it out |
Timing Edge Cases
Starts faster than 18 hours are reported when larger doses are absorbed quickly. People often remember a shared meal with several others getting sick around the same time. A slower start can show up when toxin was produced in a wound or when a small dose took longer to move through the gut. Case series describe neurologic signs unfolding several days after the event that seeded the toxin.
Linking a meal or wound to the pattern isn’t always simple. Food diaries, leftover jars, and stool or serum tests help the public health team trace a source. If an official asks for jars or labels, share them without rinsing. That evidence helps protect other households from the same batch.
Want a deeper safety refresher before your next batch day? Try our pressure cooker safety guide for clear, practical steps.