Side Effects of Amoxicillin

Health Line

02-06-2025

Amoxicillin may cause mild side effects, including stomach issues, headaches, and yeast infections. Less commonly, people may have more severe reactions like seizures.
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 of amoxicillin (Amoxil) are:
diarrhea
stomach upset
headache
abnormal taste sense
skin rash
vaginal yeast infection
Less common side effects include:
allergic reactions like itching or hives, swelling of the face, lips, or tongue
breathing problems
blistering, peeling, or loosening of the skin, including inside the mouth
dizziness
trouble sleeping
seizures
trouble passing urine, dark urine, or a decrease in the quantity of urine
unusually weak or tired
unusual bleeding or bruising
yellowing of the eyes or skin
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
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 like 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, disrupting the gut and potentially leading to diarrhea.
To treat diarrhea caused by amoxicillin, talk with a healthcare professional first to discuss the best first steps. Then, consider taking a supplement with probiotics, staying hydrated, and following the healthcare professional'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.
Stomach upset
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 abdominal pain 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.
Headache
A headache is a pain or discomfort in the head, scalp, or neck. Tight, contracted shoulders, neck, scalp, and jaw muscles likely cause the most common headaches.
Headaches are a common side effect of taking amoxicillin, and while less severe, 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.
Abnormal taste sense
Antibiotics like amoxicillin can cause taste disturbances. Sometimes, a person may find foods taste metallic when 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 taking amoxicillin. A person may also be dehydrated if they have a fever while taking antibiotics. A 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. Talk with a healthcare professional if you're having difficulty eating anything because of taste.
Skin rash
Skin rashes when taking amoxicillin can be common. Sometimes, it's hard to tell if the rash is caused by an allergy.
People may notice a skin rash after taking amoxicillin for several days. The rash may have small, flat, or raised discolored patches unevenly spaced on the skin. Sometimes, it's itchy, and it usually starts 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 medication. 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 take an antihistamine like diphenhydramine (Benadryl), it may help with the itching. Ask for a prescription for another antibiotic 'family' if you are truly allergic.
The rash should go away after a few days if it isn't an allergy. Some people may find that an anti-itch cream helps.
Vaginal yeast infection
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 or other color changes, 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 with a healthcare professional.
Less common side effects
Allergic reactions
Allergies are usually not the reason for an adverse 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. They aren't too worrisome on their own but should be observed in case symptoms worsen. Antihistamines and hydrocortisone can treat mild symptoms.
Swelling of the face, lips, or 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 discoloration. 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. Another example is strenuous exercise, especially when you do not exercise regularly.
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, slowing breathing and allowing 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 healthcare professional so you can be prescribed another medication to prevent this reaction. If breathing becomes increasingly difficult, contact your healthcare professional 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, peeling, or loosening of the skin after taking amoxicillin, contact your healthcare professional immediately.
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. However, if skin starts blistering, peeling, or loosening, seek medical attention immediately.
Do not take amoxicillin if you're allergic to penicillin to prevent severe skin irritations.
Dizziness
Dizziness occurs when you feel lightheaded and 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 healthcare professional about the medications you are currently taking before they prescribe 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. If you lie down, keep your head elevated with a pillow.
Dizziness may be a symptom of anemia or an allergic reaction.
A severe allergic reaction could be present if dizziness is combined with symptoms like shortness of breath or swelling of the lips, face, or tongue. 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 healthcare professional 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 healthcare professional. This is particularly important if it happens for longer than a day or two or if 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 healthcare professional can prescribe another type of antibiotic.
If you are prescribed amoxicillin, make sure to only take the prescribed dose within the time suggested by your healthcare professional. It's also important to drink the recommended requirement of water.
Dark urine is a severe side effect of amoxicillin. If you experience changes in your urine, talk to your healthcare professional.
Difficulty urinating
Painful urination describes any pain, discomfort, or burning sensation during urination.
Pain during urination is a fairly common problem. A urinary tract infection most often causes it.
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 healthcare professional 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 healthcare professional 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 healthcare professional 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.
Amoxicillin can also cause this effect and liver damage or injury. The liver injury can even occur after amoxicillin doses have stopped. It 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 with your healthcare professional if you experience any of these symptoms.
Before taking amoxicillin, tell your healthcare professional if you have or have ever had liver damage.
When is it an emergency?
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
How long do side effects last after taking amoxicillin?
Amoxicillin's side effects typically resolve when treatment is stopped. However, the exact length of their duration depends 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 resolve 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 a week or less.
Mild allergic reactions typically stop upon discontinuation of use and treatment with antihistamines and hydrocortisone.
Takeaway
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.