How Long Does It Take Antibiotics to Start Working?

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A person with a bacterial infection typically stops being contagious 24 hours after starting antibiotics, says the UK's National Health Service. However, the NHS also notes that the speed of antibiotic treatment depends on the type and severity of the infection. MedicineNet advises patients to contact their doctor if they do not see improvement within a few days on an antibiotic treatment.

The NHS advises patients to finish their prescribed courses of antibiotics on schedule, even if they begin to feel better, because this will ensure that all bacteria are killed. The infection may return if the patient does not complete the full treatment. Some antibiotic treatments consist of a single dose, while others require several doses over the course of a week or more.

Taking antibiotics when they are not crucial to survival leads to antibiotic resistance, says MedicineNet. Overusing antibiotics causes bacteria to become resistant to them, ultimately making the antibiotics less effective or completely ineffective. Failure to finish a course of antibiotics also contributes to antibiotic resistance, says the NHS.

Antibiotics should not be shared or stored for future use, warns MedicineNet. Doctors prescribe different antibiotics based on medical history and infection type. A treatment that works for one patient may be ineffective or dangerous for another.