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Determine rabies PEP recommendations based on exposure type, animal, and vaccination history
HRIG: 20 IU/kg (infiltrate wound + IM remainder)
Vaccine: Days 0, 3, 7, 14 (deltoid)
NO HRIG
Vaccine only: Days 0 and 3 (deltoid)
| Animal | Risk Level | PEP Recommendation | Notes |
|---|---|---|---|
| Bat | Very High | PEP unless tested negative | Leading cause of human rabies in US |
| Raccoon, Skunk, Fox | High | PEP unless tested negative | Major rabies reservoirs |
| Dog, Cat (stray/wild) | Moderate | 10-day observation or PEP | Consider local rabies prevalence |
| Dog, Cat (domestic) | Low | 10-day observation | Defer PEP pending observation |
| Livestock | Low | Consider individual case | Consult public health |
| Rodents, Rabbits | Very Low | PEP rarely indicated | Almost never require PEP in US |
Rabies is a viral disease that affects the central nervous system. Once symptoms appear, it is almost always fatal (99.9% mortality). However, rabies is preventable with prompt post-exposure prophylaxis (PEP) administered before symptoms develop. This makes timely risk assessment and treatment critical.
Bats are the leading source of human rabies deaths in the United States. Their bites may be very small and go unnoticed. PEP should be considered for any direct contact with a bat unless the bat tests negative. This includes finding a bat in a room with a sleeping person, unattended child, or intoxicated/mentally impaired person.
The rabies vaccine stimulates your immune system to produce antibodies (takes 7-14 days). HRIG (Human Rabies Immune Globulin) provides immediate passive immunity by directly providing antibodies. Previously unvaccinated people need both. Previously vaccinated people only need vaccine boosters because they can rapidly produce their own antibodies.
PEP should begin as soon as possible after exposure, ideally within 24 hours. However, it can still be effective if started later, even weeks after exposure, as long as symptoms have not appeared. The incubation period is typically 1-3 months but can range from days to years. Never delay PEP because you think "it's been too long."
Healthy dogs and cats can be observed for 10 days. If the animal remains healthy during this period, it did not have rabies virus in its saliva at the time of the bite, and PEP can be discontinued. Wild animals or animals showing signs of rabies should be euthanized and tested immediately rather than observed.
Modern rabies vaccines and HRIG are generally safe. Common side effects include injection site pain, redness, headache, muscle aches, and nausea. Serious allergic reactions are rare. The benefits of preventing rabies far outweigh any risks of the vaccine. Previous severe allergic reactions should be discussed with an allergist or infectious disease specialist.
This rabies PEP calculator provides general guidance based on CDC and WHO recommendations. Rabies risk varies by geographic region, and local epidemiology must be considered. Always consult with local or state public health authorities for region-specific recommendations. For unusual exposures (e.g., organ transplant, aerosol exposure in lab), consult infectious disease specialists. When in doubt, initiate PEP - it can be discontinued if the animal tests negative or remains healthy during observation. Rabies is almost always fatal once symptomatic, making prevention critical.