Amoxicillin for strep throat: Dosage, uses, and side effects

In this article:

• Understanding strep throat
• Will amoxicillin treat strep throat?
• Dosage
• How long does it take to work?
• Side effects and risks
• Do you need antibiotics for strep throat?
• Alternatives to amoxicillin for strep throat

In this article

• Understanding strep throat
• Will amoxicillin treat strep throat?
• Dosage
• How long does it take to work?
• Side effects and risks
• Do you need antibiotics for strep throat?
• Alternatives to amoxicillin for strep throat

Amoxicillin is a generic prescription antibiotic that’s related to penicillin. It kills a variety of bacteria and is a first-line treatment for strep throat, which is a bacterial infection of the throat. Here’s what to know if you’ve been prescribed amoxicillin for strep throat.

Understanding strep throat

If you suspect you have strep throat, it’s important to seek medical care right away. A healthcare provider can do a quick, painless throat swab to confirm that you have strep throat and get you started on the right treatment. 

Strep throat causes

Streptococcal pharyngitis (strep throat) happens when bacteria known as group A Streptococcus pyogenes multiply out of control in your throat and on your tonsils. More than 120 strains of group A Streptococcus exist, and they’re easily spread when an infected person exhales, sneezes, or coughs through microscopic respiratory droplets. If you have strep throat, you were exposed to someone who also has strep throat. It can take up to five days for symptoms to appear after exposure. 

Starting an antibiotic like amoxicillin quickly contains the spread of strep throat and decreases the length of time you are contagious. You’re no longer contagious after about 24 hours of antibiotic treatment, but it takes longer than that to completely kill the Streptococcus bacteria in your throat. 

Strep throat symptoms

Painful swallowing, a fever, a sore throat that’s dotted with red or white patches, red spots on the roof of your mouth, and/or swollen neck lymph nodes are the hallmark symptoms of strep throat. 

Other strep throat symptoms can mimic other illnesses, like the flu or a cold:

• Fever of 101 F or higher
• Chills
• Body aches
• Abdominal pain
• Nausea or vomiting
• No appetite

In some cases, strep throat causes a rash called scarlet fever. It looks like widespread red blotches that typically appear on the throat and chest first.

It’s also possible to have strep throat and not feel any symptoms at all. This means you’re a carrier: someone who “carries” and spreads the infection without realizing they’re sick. 

Will amoxicillin treat strep throat?

Yes, amoxicillin will treat strep throat. Healthcare providers consider it the best strep throat treatment because it’s highly effective and has a low risk of side effects. However, you may also need to take some over-the-counter medications to help manage strep throat symptoms while amoxicillin gets to work.

“Amoxicillin kills off the bacteria quickly to prevent long-term, very rare but very serious complications and to reduce transmission,” says Linda Yancey, MD, an infectious disease specialist at Memorial Hermann Health System. “What it will not do is make you feel better faster. The amoxicillin is not going to do a thing for the symptoms you are having right now.”

Amoxicillin is a synthetic version of penicillin, the original go-to for treating strep throat infections. By making a minor change in the structure of penicillin, scientists created an antibiotic that fights a broader range of bacteria and is less likely to fail due to antibiotic resistance. If you’re allergic to amoxicillin or can’t take it for another reason, other antibiotics also effectively treat strep throat. 

Amoxicillin for strep throat dosage

Amoxicillin is dosed by weight, age, infection type, and infection severity. The length of time the antibiotic is given is also dependent on the infection that it is treating.

Infants under 3 months old can take up to 15 milligrams (mg) of amoxicillin per kilogram (kg) of body weight every 12 hours. 

For children older than 3 months who weigh less than 40 kg (about 88 pounds), there are four different amoxicillin dosing options based on infection severity and dosage schedule:

• Up to 13.5 mg per kg of body weight every 12 hours for a mild to moderate infection
• Up to 10 mg per kg of body weight every 8 hours for a mild to moderate infection
• Up to 22.5 mg per kg of body weight every 12 hours for a severe infection
• Up to 20 mg per kg of body weight every 8 hours for a severe infection

Adults and children who weigh more than 40 kg also have four dosing options:

• 500 mg every 12 hours for a mild to moderate infection
• 250 mg every 8 hours for a mild to moderate infection
• 875 mg every 12 hours for a severe infection
• 500 mg every 8 hours for a severe infection

If you have severe kidney impairment, your healthcare provider may lower your dose as the body does not metabolize the antibiotic as fast as those with normal kidney function. 

It’s important to complete the full course of amoxicillin exactly as prescribed, especially if you have strep throat. Otherwise, you run the risk of developing complications like rheumatic fever, an autoimmune disorder that occurs when Streptococcus sp. infections aren’t properly treated. Stopping antibiotics early also increases the risk of the bacteria in your body becoming antibiotic-resistant. 

How long does amoxicillin take to work for strep throat?

Amoxicillin starts to kill bacteria within a few hours of the first dose, but it may take two or three days for you to notice significant symptom relief. 

“The usual course duration for strep throat is going to be seven to 10 days to bounce back completely,” Dr. Yancey says. “People generally feel better in three to five days.”

Amoxicillin treatment for strep throat should last for at least 10 days. When you have just a couple of days’ worth of amoxicillin left, check in with your healthcare provider to let them know how you’re feeling. You may need more amoxicillin if you’re still symptomatic, and severe infections may require several weeks of treatment, re-evaluation, or a different antibiotic. 

Amoxicillin for strep throat side effects and risks

Amoxicillin is considered a safe medication. It’s the most commonly prescribed antibiotic in the U.S., and doctors write more than 23 million prescriptions for it yearly. However, like most medications, it can cause some unwanted or serious side effects. 

According to clinical trial data, the most common side effects of amoxicillin are diarrhea, rash, vomiting, and nausea. It’s also known to cause headaches and may change the way things taste. 

In rare cases, some of these side effects develop into more severe conditions. For example, relentless or prolonged vomiting or diarrhea may indicate drug-induced enterocolitis syndrome (DIES) or Clostridioides difficile-associated diarrhea (CDAD). These intestinal conditions can be life-threatening, so seek immediate medical care if your vomiting or diarrhea gets worse or lasts more than two days, if you have urinated less than three times in 24 hours, or if you feel especially weak, have chest pain, or have shortness of breath. 

Amoxicillin-induced skin rashes should also be closely monitored. Several uncommon severe skin reactions are associated with this antibiotic, including Stevens-Johnson syndrome and toxic epidermal necrolysis. These can cause severe skin loss and may be fatal. 

Some people develop a severe allergic reaction called anaphylaxis after taking amoxicillin. Anaphylaxis is a medical emergency because the airways swell, making it impossible to breathe. Call 911 if you have swelling of your lips, tongue, face, or throat, or if you have trouble breathing or swallowing. Do not drive to the hospital if these occur; call 911, as EMTs can do life-saving measures en route to the hospital. 

Amoxicillin and antibiotic resistance

Antibiotics like amoxicillin must be carefully prescribed to prevent the development of antibiotic-resistant bacteria. Amoxicillin is actually less prone to antibiotic resistance than original penicillin, but it’s still important to follow best practices to reduce the risk of antibiotic resistance even further. 

Your healthcare provider should confirm the presence of a bacterial infection before prescribing amoxicillin. Then, it’s up to you to take the medication exactly as prescribed. Finish all of your doses, even if your strep throat goes away before the amoxicillin runs out. Otherwise, the infection may come back stronger than before. 

Do you need antibiotics for strep throat?

Yes, antibiotics are needed for strep throat. Strep throat is normally self-limited. Even without antibiotic treatment, fever and symptoms commonly resolve within a few days.  Antibiotics are given to reduce long-term complications.   If antibiotics are not given within a week, untreated strep throat can lead to additional infections, kidney inflammation (which rarely causes kidney failure), or rheumatic fever (causing multisystem inflammation of the joints, heart muscle, or heart valves), especially in children.

“Amoxicillin is absolutely the first line of treatment for strep throat,” says Dr. Yancey. “It works across the board for non-allergic patients who have strep throat. It’s the drug of choice and the right thing to do. It will prevent heart disease and kidney disease.”

Alternatives to amoxicillin for strep throat

Your healthcare provider is unlikely to recommend an alternative to amoxicillin for strep throat unless you’re allergic to it or have severe kidney damage. “Amoxicillin is the drug of choice for a reason,” Dr. Yancey says. “It’s the most effective and has the best side effect profile.”

Bruce Hirsch, MD, an infectious disease physician and board member of the Peggy Lillis Foundation, adds that there are many other antibiotics that can safely treat strep throat in people with penicillin/amoxicillin allergies. However, there are side effects and risks associated with each.

“Antibiotics kill off the bad germs but also impact all the billions of germs that live on and in our bodies and crowd out even worse bacteria,” Dr. Hirsch explains. One of the “bad” bacteria that’s kept in check by “good” bacteria is Clostridioides difficile, or C. diff. When this particular bacterium grows too much in the gut, it can cause severe diarrhea and a potentially life-threatening gastrointestinal condition called toxic colitis. Certain antibiotics are more likely to trigger a C. diff infection, so care must be taken to find the best treatment for each individual.

“Clindamycin is particularly likely to cause C. diff,” Dr. Hirsch says. “Figuring out if there is a true penicillin allergy makes a big difference in getting the right antibiotic for the right condition.”

Your healthcare provider may consider the following antibiotics instead of amoxicillin: 

• Macrolides:  A class of antibiotics often prescribed when people are allergic to penicillin and its derivatives. Examples include azithromycin and clarithromycin.
• Cephalosporins: A class of antibiotics that have long been approved for the treatment of strep throat. Examples include cefadroxil and cefixime. 

While prescription antibiotics offer crucial protection against streptococcus complications, they may not provide the fast symptom relief you’re looking for. Consider over-the-counter pain relievers and fever reducers like acetaminophen (Tylenol) or ibuprofen (Advil) to make symptoms more tolerable. 

The bottom line 

Amoxicillin is an effective and typically well-tolerated antibiotic that’s considered the best option for strep throat. Your healthcare provider may prescribe a different antibiotic if you’ve had an allergic reaction to amoxicillin. 

Don’t try to battle through strep throat without being evaluated by a medical professional. You’re less likely to spread this highly contagious infection or experience serious complications while taking an antibiotic like Amoxicillin. If you don’t have insurance, use a SingleCare coupon to make sure you get the best deal.