How Long Is Strep Contagious?

How long strep throat is contagious depends on whether or not the infection, caused by the bacteria group Streptococcus pyogenes, is treated with antibiotics.

Generally speaking, a person with untreated strep can remain contagious for two to three weeks, while a person who takes antibiotics for strep stops being contagious within 48 hours of starting treatment.

If you have been prescribed antibiotics for strep, it's important to finish the full course of medication—even if your symptoms resolve before the course is done. Taking your antibiotics as directed prevents complications and helps stop the spread.

This article explores how long strep throat is contagious and how it's treated. It also provides a few tips to reduce your risk of catching strep.

How Long Is Strep Throat Contagious?

Individuals with strep throat can be contagious for a few days before they start showing symptoms. This means that someone who has not gotten sick yet can spread the infection.

If a person is prescribed antibiotics for strep, they usually stop being contagious within 24 to 48 hours of starting treatment. If their strep is not treated with antibiotics, however, they can remain contagious for two to three weeks.

Some people with strep do not develop symptoms and may not feel sick at all. Although people with asymptomatic (symptom-free) strep are much less likely to be contagious, it's still possible for them to infect others.

Causes

The bacteria that causes strep throat, Streptococcus pyogenes, spreads from person to person through saliva or secretions that contain the bacteria. People can also pass strep throat through coughing, sneezing, and touching people or contaminated objects (e.g. doorknobs, door handles, and utensils).

Although it is possible to get strep throat from eating contaminated food or milk, it's very rare. There is no evidence that you can catch strep from your pet, either.

Risk Factors

Some factors can increase your risk of contracting strep throat. They include:

• Young age: Strep throat occurs frequently in children ages 5 to 15 and is rare in children under 3.
• Close contact/spending time in crowded settings: This includes spending time with someone who has strep throat in schools, daycare centers, or large venues.
• The time of year: Strep throat can occur year-round, but it has seasonal variations. Infections are more common in late winter and early spring.
• Genetics: According to a 2019 study, researchers found that kids with recurring strep throat tended to have smaller germinal centers in their tonsils, which usually recognize and fight infections. They also were more likely to have family members who had tonsillectomies (surgical removal of the tonsils).
• Weakened immune system: This increases the susceptibility for people to get strep throat.
  

Treatment

Antibiotics are the most commonly used medications to treat bacterial infections by preventing them from growing or killing them. To treat strep throat, your healthcare provider may prescribe penicillin or amoxicillin.

However, if you are allergic to penicillin, your doctor may prescribe a cephalosporin such as Keflex (cephalexin) or medication from a different “family” of antibiotic drugs that is unlike penicillin.

Additionally, someone who tests positive for strep throat but has no symptoms (called a carrier) does not typically need antibiotics. This is because carriers are less likely to spread the bacteria to others and very unlikely to develop complications.

However, always consult your healthcare professional if you believe you or someone you know may be a carrier for strep throat to determine the best course of treatment.

The benefits of antibiotics include:

• Decreasing how long someone is sick
• Decreasing symptoms
• Preventing the bacteria from spreading to others
• Preventing serious complications such as rheumatic fever

It is essential to finish your course of antibiotics even if you are feeling better, as the remaining bacteria can continue to multiply. When this happens, bacteria can become resistant to the antibiotics, and cause further harm to the body. In some cases, it can develop into sepsis (blood infection), which is a life-threatening condition.

When to See a Doctor

While strep throat is not usually dangerous, it can sometimes cause medical emergencies. However, this is rare. Seek medical care immediately if you have strep throat and experience the following signs and symptoms:

• Trouble breathing or shortness of breath
• Dizziness, feeling faint, or passing out
• Blue or pale lips or fingers
• Trouble swallowing

Prevention

People can get strep throat more than once. Having strep throat does not protect someone from getting it again in the future. While there is no vaccine to prevent strep throat, there are things people can do to protect themselves and others:

• Practice good hygiene: This includes washing your hands often (with soap and warm water for at least 20 seconds), especially after coughing or sneezing and before preparing food or eating. You should also wash glasses and utensils after a person who is sick uses them. Practicing good hygiene is the best way to keep from getting or spreading group A strep.
  
• Stay home and take your antibiotics if you have strep throat: Your healthcare provider will likely prescribe antibiotics for strep throat. Stay home from work or school until you no longer have a fever and have taken antibiotics for at least 12 hours.

Summary

Once a person starts taking antibiotics for strep, they typically stop being contagious within 48 hours. If a person with strep does not take antibiotics, they can remain contagious for as many as three weeks.

Symptoms are not always a good gauge of how contagious someone with strep is, since some people with asymptomatic strep are still contagious. If you are taking antibiotics for strep, it's critical that you finish the full course, even if your symptoms resolve before the course is done.

Taking antibiotics exactly as prescribed stops the spread of infection to others and significantly reduces the risk of complications, such as sepsis and antibiotic resistance.