Amoxicillin is a penicillin antibiotic used to treat bacterial infections, including bronchitis, pneumonia, and infections of the ear, nose, throat, skin, and urinary tract. Though it can be highly effective in treating bacterial infections, it also comes with a list of potential side effects.

Among the more common side effects for amoxicillin (Amoxil) are:

Less common side effects include:

Can you overdose?

Taking more than your prescribed dose of amoxicillin is unlikely to cause harm and treatment is not typically needed for an antibiotic overdose.

While acute renal toxicity may occur, it is rare.

According to an observation of 285 patients taking amoxicillin from 2014 to 2015, 10 people (18 percent) developed acute kidney issues related to the amoxicillin. It is important to note that this observation occurred in patients with severe infections who received IV amoxicillin at high doses. These patients were not receiving oral amoxicillin for more common infections.

Diarrhea is loose, watery, and frequent stool. Diarrhea is considered chronic when you have had loose or frequent stools for more than 2 weeks.

Drink plenty of fluids to avoid becoming dehydrated. Drinking milk or other fluids such as water may be fine for mild diarrhea. For moderate and severe diarrhea, electrolyte solutions — available online and in drugstores — are usually best.

Diarrhea is a common side effect of amoxicillin. All antibiotics kill off the normal bacteria in our guts which disrupts the gut and can lead to diarrhea.

To treat diarrhea caused by amoxicillin, talk to a doctor first to discuss the best first steps. Then, consider a supplement with probiotics and stay hydrated, in addition to the doctor’s recommendation.

Diarrhea is typically considered a common side effect, but if you’re becoming dehydrated or noticing streaks of blood in diarrhea, seek immediate medical attention.

Abdominal pain is pain that you feel anywhere between your chest and groin. This is often referred to as the stomach region or belly.

Almost everyone experiences pain in the abdomen at one time or another. Most of the time, it is not caused by a serious medical problem. Stomach discomfort or nausea is a common side effect of amoxicillin. Less common symptoms include abdominal pain and vomiting.

Taking your dose of amoxicillin with a meal may help prevent this side effect.

To cope with an upset stomach, eat bland, easy-to-digest foods like soups, crackers, and toast. Peppermint is thought to help upset stomach symptoms. You can take anti-nausea medication if necessary.

If you experience severe, prolonged abdominal pain or see blood in your vomit or stool, seek immediate medical attention.

A headache is pain or discomfort in the head, scalp, or neck. The most common headaches are most likely caused by tight, contracted muscles in your shoulders, neck, scalp, and jaw.

Headaches are a common side effect of taking amoxicillin, and while less serious, are a frequent occurrence.

Taking your dosages with food and drinking an adequate amount of water can help prevent headaches caused by amoxicillin.

Headache and migraine medications, including Tylenol and Aleve, can help to relieve headaches caused by amoxicillin.

Antibiotics like amoxicillin can cause taste disturbances. Sometimes, a person may find foods taste metallic when they are taking amoxicillin. One possible reason is the medication can affect how well the body absorbs the mineral zinc. A zinc deficiency can cause a bad or metallic taste in the mouth.

Other people may find they are more sensitive to sweet or salty tastes when they are taking amoxicillin. A person may also be dehydrated if they have a fever while they’re taking antibiotics. Dry mouth can affect a person’s taste sensations, too.

Most of the time, these side effects go away when you stop taking amoxicillin. Drinking more water to stay hydrated can help. If you’re having a hard time eating anything because of taste, talk to a doctor.

Skin rashes when taking amoxicillin can be common. Sometimes it’s hard to tell if the rash is because of an allergy or not.

People may notice a skin rash while taking amoxicillin after they’ve taken it for several days. The rash may have small, flat, or raised discolored patches unevenly spaced on the skin. Sometimes, they’re itchy and usually start on the chest, stomach, or back.

The rash from amoxicillin is different from an allergic reaction or hives. Hives are raised, itchy, welts that usually pop up within hours after taking the medicine. A person may also have symptoms such as trouble breathing or swallowing.

If you have a true allergic reaction to amoxicillin, seek emergency medical attention if you are having problems breathing. If you can take an antihistamine like diphenhydramine (Benadryl), it may help the itching. Ask for a prescription for another antibiotic “family” if you are truly allergic.

If the rash isn’t an allergy, it should go away after a few days. Some people may find that an anti-itch cream helps.

Amoxicillin works well because it can keep bacteria from growing. Unfortunately, sometimes that extends to “healthy” bacteria that maintain pH balance in the vagina. As a result, a person’s vaginal pH may become disturbed where yeast can thrive, and a yeast infection can result.

Signs of a yeast infection include itching, redness, and cottage cheese-like discharge. Over-the-counter medications are available to treat yeast infections. If you aren’t sure if it’s a yeast infection or another infection type, you should talk to a doctor.

Allergic reactions

Allergies are usually not the reason for a negative reaction to a drug. In fact, allergic reactions are an uncommon occurrence. Though it may seem like an allergic reaction, it is really a nonallergic adverse reaction.

Mild allergic reactions include itching and hives. Mild allergic reactions aren’t too worrisome on their own but should be observed in case symptoms worsen. Mild symptoms can be treated with antihistamines and hydrocortisone.

Swelling of the face, lips, tongue, and shortness of breath are signs of a severe allergic reaction. If you experience a severe allergic reaction, seek medical attention immediately.

If an allergic reaction occurs, monitor the spreading of the rash or redness. Amoxicillin can cause delayed allergic reactions even after you’ve stopped taking it.

Breathing problems

Breathing difficulty involves a sensation of difficult or uncomfortable breathing or a feeling of not getting enough air.

In some circumstances, a small degree of breathing difficulty may be normal. Severe nasal congestion is one example. Strenuous exercise, especially when you do not exercise regularly, is another example.

If you have difficulty breathing, you could be experiencing an allergic reaction to amoxicillin.

If you’re experiencing mild breathing problems, you can try to ease breathing by doing the following:

  • Breathe through pursed lips, which slows down breathing and allows for deeper breaths.
  • Perform activities at a comfortable pace; avoid rushing.
  • Try not to hold your breath.

If you are allergic to amoxicillin or penicillin, inform your doctor so you can be prescribed another medication to prevent this reaction. If breathing becomes increasingly difficult, contact your doctor right away.

If you have difficulty breathing and swelling of your lips, face, mouth, or throat, call 911 or go to the emergency room.

Blisters and other skin problems

Blisters are small, raised lesions where fluid has collected under the skin. They may be caused by an allergic reaction, burns, frostbite, or by excessive friction or trauma to the skin. Blisters may also be a symptom of a systemic illness, or of a specific skin disorder.

This side effect is somewhat rare, but serious when it does occur. If you experience discoloration, blistering, or peeling or loosening of the skin after taking amoxicillin, contact your doctor right away.

Home treatments may be used to manage mild, non-itching rashes that are not severe. Treatment includes antihistamines or hydrocortisone, oatmeal baths, and drinking lots of water. If skin starts blistering, peeling, or loosening, however, seek medical attention immediately.

To prevent severe skin irritations, do not take amoxicillin if you’re allergic to penicillin.

Dizziness

Dizziness occurs when you feel lightheaded, unsteady, or you experience a loss of balance or vertigo (a feeling that you or the room is spinning or moving).

Most causes of dizziness are not serious and either quickly get better on their own or are easily treated.

Tell your doctor all of the medications you are currently taking before they prescribe you amoxicillin. To prevent dizziness, avoid drinking alcohol when on amoxicillin.

Avoid driving until you know how amoxicillin will affect you. If you get dizzy, sit down for a moment and see if it passes. Keep your head elevated with a pillow if you lie down.

Dizziness may be a symptom of anemia or an allergic reaction.

If dizziness is severe or combined with symptoms like shortness of breath or swelling of the lips, face, or tongue, a severe allergic reaction could be present. Seek immediate medical attention.

Trouble sleeping

Sleeping difficulty, called insomnia, can involve difficulty falling asleep when you first go to bed at night, waking up too early in the morning, and waking up often during the night.

Everyone has an occasional sleepless night, and this is not a problem for most people. However, as many as 25 percent of Americans a year experience acute insomnia, and insomnia is a chronic problem for many people.

Seizures

A seizure is a sudden change in behavior characterized by changes in sensory perception (sense of feeling) or motor activity (movement) due to an abnormal firing of nerve cells in the brain. Epilepsy is a condition characterized by recurrent seizures that may include repetitive muscle jerking called convulsions.

If you are experiencing this side effect, contact your doctor as soon as possible.

Dark urine

Normal urine is often a pale or straw yellow color. When urine strays from this color, it is considered abnormal. Abnormally colored urine may be cloudy, dark, or blood-tinged.

Any changes in urine color, or the presence of an abnormal urine color that cannot be linked to the consumption of a food or drug, should be reported to your doctor. This is particularly important if it happens for longer than a day or two, or you have repeated episodes.

Dark urine can be caused by amoxicillin due to changes in blood, liver, and/or kidney function. Renal toxicity is rare, but when it does occur, it can be serious.

Those at risk for kidney complications in particular should not use amoxicillin to prevent this side effect and potential kidney damage. Your doctor can prescribe another type of antibiotic.

If you are prescribed amoxicillin, make sure to only take the prescribed dose within the amount of time suggested by your doctor. It’s also important to drink the recommended requirement of water.

Dark urine is a severe side effect of amoxicillin. Talk to your doctor if you experience changes in your urine.

Difficulty urinating

Painful urination describes any pain, discomfort, or burning sensation during urination.

Pain during urination is a fairly common problem. It is most often caused by a urinary tract infection.

Amoxicillin may cause crystals to form in the urine. These crystals are directly tied to amoxicillin and look very different than crystals otherwise commonly found in urine. It can also happen in rare cases where the kidney is negatively impacted.

To prevent this, never take more than your prescribed dose and drink plenty of water. If you’re experiencing slight discomfort when you urinate, drink water and reduce the amount of protein in your diet.

Painful urination can also indicate renal failure or damage. Contact your doctor right away if you experience this.

Unusual bleeding or bruising

Bleeding under the skin can occur from broken blood vessels that form tiny pinpoint red or discolored dots (called petechiae). Blood can also collect under the tissue in larger flat areas (called purpura), or in a very large bruised area (called an ecchymosis).

Amoxicillin can increase the risk of bleeding. If you’re experiencing either unusual bleeding or bruising, see a doctor immediately. Internal bleeding may be occurring, which could lead to bleeding in the digestive system, or, in rare cases, the brain.

To prevent this, tell your doctor if you’re on anticoagulants or blood thinners before you start taking amoxicillin.

If you experience this side effect of amoxicillin, it’s considered a rare but serious side effect. Seek medical attention as soon as possible.

Yellowing of the eyes or skin

Jaundice is a yellow color in the skin, mucous membranes, or eyes. The yellow pigment is from bilirubin, a byproduct of old red blood cells. If you’ve ever had a bruise, you may have noticed that the skin went through a series of color changes as it healed. When you saw yellow in the bruise, you were seeing bilirubin.

This effect, and liver damage or injury, can also be caused by amoxicillin. The liver injury can even occur after amoxicillin doses have stopped. This is more likely to happen when taking amoxicillin with clavulanate.

Recognizing early symptoms such as fatigue, poor appetite, and vomiting can help prevent jaundice from worsening. Talk to your doctor if you experience any of these symptoms.

Before taking amoxicillin, tell your doctor if you have or have ever had liver damage.

Taking an extra dose of amoxicillin will not typically cause harm, but there are certain symptoms to look out for that merit immediate medical attention.

You should call 911 or the poison control helpline at 800-222-1222 if you experience any of the following symptoms after taking more than your prescribed dose of amoxicillin:

  • stomach pain
  • vomiting
  • bloody or cloudy urine
  • difficulty urinating
  • decreased urination
  • confusion

Side effects of amoxicillin will typically reside when you stop treatment. However, exactly how long they last depend on the side effects.

  • Antibiotic-associated diarrhea may occur for a few hours for up to 2 months after antibiotic intake. Probiotic therapy may help to treat it.
  • Vaginal yeast infections typically reside after treatment with an antifungal medication, done over the course of 1 to 7 days.
  • Sense of taste tends to return to normal when treatment is stopped.
  • Skin rashes usually begin on the fifth day of taking the drug and last for an average of 3 days but can range from 1 to 6 days.
  • Mild allergic reactions typically stop upon discontinuation of use and treatment with antihistamines and hydrocortisone.

Amoxicillin is a commonly prescribed antibiotic in the penicillin family used to treat a range of bacterial infections. Side effects of amoxicillin are typically mild, and include gastrointestinal issues like upset stomach and diarrhea as well as headache, rash, abnormal taste, and vaginal yeast infections. Less common side effects like allergic reactions, breathing problems, and seizures have also been recorded.

If you experience severe side effects or any of the described overdose symptoms when taking amoxicillin, be sure to contact your doctor, 911, or poison control.