Strep Throat And Cephalexin: What You Should Know

Sore throat is a common ailment among people of all ages. Usually, it brings about discomfort but is not a cause for concern as it's easy to treat with home remedies and over-the-counter drugs. However, if your scratchy or painful throat is accompanied by other symptoms, you may have strep throat.

Fortunately, medical professionals are well-equipped to diagnose¹ strep throat and provide the necessary treatments to help you feel better. In this article, we’ll detail everything you need to know about strep throat and whether cephalexin is an effective treatment option.

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What is strep throat?

Strep throat also referred to as streptococcal pharyngitis, is an infection of the tonsils and throat caused by a group of bacteria known as Streptococcus pyogenes or group A streptococcus (group A strep). These bacteria live in the throat and nose and can easily pass to others through coughing, talking, sneezing, or touching shared surfaces or infected skin sores.

Once exposed to group A strep, it takes two to five days to become ill. It is vital to note that not every person infected with strep throat experiences symptoms or feels unwell. However, those who exhibit symptoms are more likely to infect others than those who don’t feel sick.

Symptoms of strep throat

Symptoms can vary, but the most common signs of strep throat include:

  • Swollen and inflamed lymph nodes

  • Tiny red spots on the roof of the mouth

  • Headache

  • Rash

  • Fever

  • A painful throat that develops quickly

  • Significant pain when swallowing

  • Inflamed tonsils with white pus

  • Body aches

  • Vomiting or nausea, especially in young children

Most sore throats are caused by viruses, not bacteria. If you have a sore throat with a cough, pink eye, voice hoarseness, or a runny nose, your sore throat is most likely viral and not caused by strep. Even so, it’s best to consult a doctor just in case, as strep is highly contagious. 

Risk factors for strep throat

Strep throat can infect anyone, but school-aged children are affected more often than adults. The condition is very rare among children under three years. When it comes to adults, those who are most likely to get strep throat are:

  • Those with children in school

  • Those who frequently spend time around children

The most common mode of infection is through contact with someone infected with strep throat. Like other bacterial infections, strep throat spreads quickly in large crowds, including daycare facilities, schools, or military training grounds. 

Diagnosing strep throat

Your doctor will need to see you in person to diagnose you with strep throat. They’ll ask about your symptoms and then proceed to a physical exam, which may include a throat swab (rapid strep test) or a throat culture. 

A rapid throat test involves taking a swab of the throat and conducting tests on the swab to determine whether group A strep is the cause of the condition. The entire process is carried out on the spot, and you won’t need to wait for results from a lab. If the rapid test is positive, the doctor will prescribe antibiotics. Alternatively, if it’s negative and the healthcare provider still suspects strep throat, they’ll collect a throat culture, where a swab is sent to a lab to check for strep bacteria. Results from a throat culture can take up to two days, but the results are more accurate than a rapid test.

A throat culture is usually conducted on children and teens because strep throat can develop into rheumatic fever² if left untreated.

Complications of strep throat

If you suspect you have strep throat, see your doctor promptly to start treatment and reduce your risk of complications. If it’s not appropriately treated, strep throat can lead to:  

  • Kidney problems

  • Presence of pus pockets in the neck or around the tonsils

  • Sinusitis (sinus infection)

  • Rheumatic fever, which can cause heart problems

  • Swollen lymph nodes around the neck region

  • Meningitis (inflammation of the fluid surrounding the brain and spinal cord)

  • PANDAS (pediatric autoimmune neuropsychiatric disorders)

Treating strep throat

Oral antibiotics, like amoxicillin or penicillin, are the most common and effective treatment for strep throat. Not only do they decrease the severity and duration of the symptoms, but antibiotics also reduce the risk of spreading to others and prevent complications. Most people start to feel better a day or two³ after starting antibiotics. However, you should only take antibiotics if your healthcare provider advises it. If your strep test was negative and your sore throat is caused by a virus, antibiotics won’t help, and they can cause unwanted side effects. 

Antibiotics for strep throat

Antibiotic prescriptions vary depending on weight and age. A medical professional will prescribe a tailored dose that aligns with the following CDC guidelines:⁴

Penicillin V (oral)

  • Children: 250mg two to three times per day (maximum ten days)

  • Teenagers and adults: 250mg four times per day or 500mg twice a day (maximum ten days)

Amoxicillin (oral)

  • Children, teenagers, and adults: 500mg twice per day or 1000mg once per day (maximum ten days) 

Benzathine penicillin G (injection)

  • People weighing less than 27kg: A single 600,000-unit dose

  • People weighing 27kg or more: A single 1,200,000-unit dose

Alternatives may be prescribed for people with a penicillin allergy. 

Non-antibiotic options for strep throat

If you suspect you have strep throat, your doctor will decide if you need antibiotics. Antibiotics are effective in slowing or stopping bacterial growth, and you should take them as prescribed by your doctor. However, it’s essential to note that antibiotics aren’t the only treatment to help you feel better while you have strep throat. In addition to antibiotics, there are steps you can take to get back to normal even sooner: 

Taking over-the-counter painkillers

It’s unlikely your doctor will prescribe pain medications to relieve your strep throat. However, if you’re exceptionally uncomfortable, over-the-counter pain medications can help. Some painkillers aren’t suitable for children, people taking certain medications, or those with specific health issues. If you’re not sure which over-the-counter treatments are right for you, ask your healthcare provider to recommend one.


Adequate sleep is crucial for recovery. If you test positive for strep, you should stay home and rest. Keep in mind that strep is contagious, so while it’s essential to rest so your body can recover, it’s also necessary to reduce the risk of spreading strep to others. Ask your doctor when you can return to school, work, or social activities. 

Staying hydrated

Drinking enough water ensures your throat is well-lubricated and moist to ease swallowing. 

Gargling warm salt water

Adults and children who are old enough to gargle without swallowing can gargle and swish a mixture of approximately one-quarter teaspoon of salt with eight ounces of warm water. Remember to spit it out when you’re done.

Eating foods that are easy to swallow

One of the symptoms of strep throat is pain while swallowing. You may find it easier to eat soft and soothing foods, including soups, mashed potatoes, broths, applesauce, yogurt, soft-cooked eggs, soft fruits, and cooked cereals. Warm (not hot) foods can alleviate throat soreness, and likewise, cold and frozen foods can offer temporary relief. Avoid spicy and acidic foods.

Eating healthy foods

No matter your ailment, eating well can help improve your condition and accelerate recovery. Skip the hard healthy foods that may aggravate your irritated throat. 

Drinking warm water or tea with honey

Due to its antibacterial properties,⁵ honey has been used to treat a variety of conditions since ancient times. For strep throat, stir two tablespoons of honey in tea or warm water until dissolved. You can sip on the mixture as needed for relief throughout the day; however, this remedy is not suitable for children under one as they’re at risk for botulism, which can be severe or fatal. 

Using a humidifier

Use a cool-mist humidifier to add moisture to the air and ease discomfort and dryness in your throat. You can also use saline nasal sprays to moisten the inner linings of your nose and mouth and clear up sinus airways. Clean your humidifier regularly, as the moist environment is well-suited for mold and bacteria growth.

Avoiding irritants

Cigarette smoke, paint fumes, cleaning chemicals, and other strong smells and substances can cause or worsen throat irritation. 

Taking supplements

Some supplements have antibacterial properties. Others reduce inflammation and soothe irritation. Common supplements for strep throat include echinacea, elderberry, vitamin C, and vitamin D. If you have any other health conditions or you’re taking medications, ask your doctor about possible interactions before adding supplements to your routine. 

Using essential oils

Ingesting essential oils like peppermint oil, naturally-occurring menthol, thyme oil, and lemon can help decrease swelling in your throat. Simply add one or two drops of your preferred essential oils to your herbal tea or water. Remember, not all essential oils are food-grade. Some are intended for external use only. Check the bottle before adding essential oils to your drink. If you’re unsure, try a prepared mint, thyme, or lemon tea, instead. You may also add some drops of essential oil to your bath water to alleviate body aches. 

Sipping chamomile tea

Many herbal teas have health-boosting properties. A warm cup of herbal tea can have immense benefits for your sore throat.

Specifically, chamomile tea has antioxidant and anti-inflammatory properties⁶ that can help improve a sore throat. Drink a cup of chamomile tea to relieve the symptoms associated with strep. You can likely enhance the effects by sweetening your tea with honey. Although chamomile tea is unlikely to harm you while you recover from strep throat, more research is needed to establish the benefits of chamomile for treating strep, in particular. 

When is cephalexin used to treat strep throat?

Amoxicillin and penicillin are the most common antibiotics prescribed to treat strep throat. Research⁷ indicates that group A strep has not yet shown resistance to penicillin. On the other hand, there is evidence the bacteria have developed resistance to both clarithromycin and amoxicillin.

People with penicillin allergies can use cephalexin for strep throat. Cephalexin works by preventing the cell walls of bacteria from growing and subsequently preventing them from replicating. Cephalexin is also effective in fighting the bacteria that cause:

  • Sinus infections

  • Respiratory tract infections

  • Soft tissue and skin infections

  • Middle ear infections

  • Urinary tract infections

How to use cephalexin

Cephalexin is available in the form of tablets, liquid, and capsules, all taken orally. If you take the liquid alternative, ensure you store it in a cool place and always shake it before use. Likewise, tablets and capsules should be stored in a cool and dry place. Tablets and capsules should be taken whole with water. Always keep all medications out of children’s reach.

Per the CDC guidelines cited above, a doctor will prescribe cephalexin at a dose of 20mg/kg of body weight (up to 500mg) twice daily for a maximum of ten days. If you forget to take a dose of cephalexin, take it as soon as possible or at the next dosing window. Don’t double your dosage to make up for a missed dose. 

Side effects of cephalexin

Like all medications, cephalexin carries a risk of side effects. Common side effects include:

  • Dizziness

  • Diarrhea

  • Fatigue

  • Stomach aches

  • Headaches

  • Vomiting

  • Nausea

  • Joint and abdominal pain

  • Vaginal discharge or itchiness

  • Red or purple rashes and itchy, yellow skin

  • Easy swelling

  • Shortness of breath or lightheadedness

  • Dark-colored urine

  • Fever

If you experience side effects that don’t improve with time or affect your daily functioning, reach out to your healthcare provider for guidance. Note that you should not use cephalexin for strep throat if you have any of the following conditions:

  • Liver disease

  • Kidney disease

  • Colitis

  • Seizure disorders

People undergoing dialysis treatments and those who are pregnant should inform their doctor of their condition before seeking a prescription for cephalexin or other antibiotics. 

Cephalexin interactions

People taking cephalexin should exercise caution when considering taking other medications and supplements. Compared to other antibiotics, cephalexin for strep throat has limited interactions with other medicines. Nevertheless, people taking cephalexin should avoid:


Metformin is among the most prescribed drugs in the United States. It is most frequently used to regulate blood sugar levels in people with type 2 diabetes. Cephalexin may increase metformin levels in the body by slowing elimination through the kidneys. This interaction is noted in the cephalexin labeling; however, few additional details are provided.

Note that metformin seldom causes low blood sugar (hypoglycemia) on its own. However, when combined with other medications, including cephalexin, the risk is significantly higher. Therefore, while using metformin alongside cephalexin, your doctor may advise you to check your blood sugar levels more often.


Warfarin is a blood thinner commonly prescribed to prevent and treat blood clots. When taking warfarin, many medications and foods can cause an increase in the risk of bleeding by boosting the blood thinning effect of warfarin. In contrast, other drugs can make warfarin less efficient, increasing the risk of blood clots. 

Cephalexin is one of the drugs that increase the risk of bleeding when taken with warfarin, so your doctor will perform frequent blood tests and encourage you to watch for signs of excessive blood thinning, including bruising or bleeding.


Probenecid is an effective drug used to treat gout. Probenecid can boost cephalexin levels in the body, which increases the risks of side effects. Further, high cephalexin levels can increase stress on the kidneys, especially in people with underlying kidney conditions. Many doctors advise against taking the two drugs simultaneously.

Some vaccines

Antibiotics, including cephalexin, can render the bacille Calmette-Guerin (BCG) tuberculosis vaccine, and those against typhoid and cholera, less effective. If you’re taking antibiotics, your body is less likely to build a robust immune response to fight the associated diseases. Speak with your doctor if you’re planning to get a vaccine and are currently taking (or have recently taken) antibiotics. They’ll advise if you need to wait and for how long. 


Drinking alcohol while taking cephalexin can worsen the drug’s side effects, which include low blood pressure, facial flushing, swelling in the mouth and face, vomiting, and nausea. Therefore, it’s best to avoid alcohol while taking this antibiotic.

Zinc supplements

Although supplements can help relieve sore throat symptoms, you should avoid taking zinc supplements as they decrease cephalexin absorption within the body. As a result, cephalexin may be less efficient in fighting infections. Take zinc supplements at least three hours after cephalexin to ensure maximum antibiotic function.

Cephalexin vs. amoxicillin: Which is more effective?

Antibiotics are effective in treating bacterial infections. A beta-lactam antibiotic,⁸ penicillin damages the cell walls of bacteria and prevents them from reproducing so the body can clear itself of the illness. 

There are many other classes of antibiotics. Cephalexin belongs to another group of beta-lactam antibiotics called cephalosporins. 

Amoxicillin and cephalexin are among the most popular antibiotics prescribed to patients. While they’re both beta-lactam antibiotics (amoxicillin belongs to the penicillin class), the drugs target different types of bacteria. When it comes to strep throat, cephalexin is more effective than amoxicillin. Even so, Amoxicillin remains the recommended first-line treatment option for strep throat, and cephalexin is the choice for a patient with a penicillin allergy..  

How to prevent the spread of strep throat

Getting strep throat once doesn’t prevent you from getting it again. So, even if you’ve had strep, you should take the appropriate precautions to avoid getting it again. If you have strep, you can prevent your close contacts, friends, and family from getting the infection by:

  • Using soap and water to wash hands often for a minimum of twenty seconds

  • Coughing and sneezing into your elbow, upper sleeve, tissue, or handkerchief instead of your hand

  • Using an alcohol-based sanitizer when it’s not practical to wash your hands

  • Avoiding sharing food, utensils, drinks, pillowcases, clothes, and towels with infected persons

When to see a doctor

If you suspect either you or your child has strep throat, make an appointment with your healthcare provider. Some symptoms, including difficulty swallowing or breathing, a fever above 101 degrees Fahrenheit, a headache, or a red or purple rash, require urgent medical attention. 

The lowdown

When using cephalexin for strep throat, it is vital to understand how and when to take it for optimal results. You should always take antibiotics exactly as prescribed to avoid complications. If you suspect that you or your child has strep throat, don’t hesitate to seek medical attention. While strep can improve without antibiotics, the drugs reduce the risk of complications and will help you feel better sooner.

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