Antibiotics are prescription drugs that help treat infections caused by bacteria. Antibiotics work by killing the bacteria that are causing an infection or by stopping them from growing and multiplying. However, they can sometimes cause side effects.
Some of the more common infections treated with antibiotics include bronchitis, pneumonia, and urinary tract infections.
Antibiotics only work to treat bacterial infections. They don’t work for infections caused by viruses, which can include:
- common cold
- runny nose
- most coughs and bronchitis
- flu
There are many different classes of antibiotics. These classes have side effects and typically affect men and women the same way. However, certain side effects are more common from some antibiotics than from others.
Read on to learn about common side effects, how to manage them, and which antibiotics are more likely to cause them.
Some side effects are more common than others.
Stomach upset
Many antibiotics cause stomach upset or other gastrointestinal side effects. These can include:
Macrolide antibiotics, cephalosporins, penicillins, and fluoroquinolones may
What to do
Ask your doctor or pharmacist whether to take your antibiotic with food. Eating can help reduce stomach side effects from certain antibiotics, such as amoxicillin and doxycycline (Doryx).
However, some antibiotics, such as tetracycline, must be taken on an empty stomach. Talk to your doctor to make sure you know how you’re supposed to take your drug and if there are other ways you can ease stomach side effects.
When to call your doctor
Mild diarrhea usually clears up after you stop taking the drug. However, if the diarrhea is severe, it may cause:
- abdominal pain and cramping
- fever
- nausea
- mucus or blood in your stool
These symptoms can be caused by an overgrowth of harmful bacteria in your intestines. If you experience the symptoms, call your doctor right away.
Photosensitivity
If you’re taking an antibiotic such as tetracycline, your body
Photosensitivity should go away after you finish taking the antibiotic.
What to do
If you know you’ll be out in the sun, take certain precautions to stay safe and comfortable. Wear sunscreen with UVA and UVB protection, and reapply sunscreen as directed on the label. Also, wear protective clothing and accessories, such as a hat and sunglasses.
Fever
Fevers are a common side effect of many medications, including antibiotics. A fever may be an allergic reaction to a medication or a side effect.
Drug fevers are very rare and typically occur as part of a syndrome. They are more common with the following:
- beta-lactams
- cephalexin
- minocycline
- sulfonamides
What to do
If you get a fever while taking an antibiotic, it will likely go away on its own. If you had the fever prior to starting the antibiotic, and you don’t develop any other symptoms, it will likely resolve in 24-48 hours. If your fever doesn’t go away after 24 to 48 hours, ask your doctor or pharmacist about using over-the-counter pain relievers such as acetaminophen (Tylenol) or ibuprofen (Motrin) to help reduce it.
When to call your doctor
If you have a fever higher than 104°F (40°C), a skin rash, or trouble breathing, call your doctor or 911 right away.
Vaginal yeast infection
Antibiotics decrease the amount of a helpful bacteria called Lactobacillus in the vagina. This “good bacteria” helps keep a naturally occurring fungus called Candida in check. When this natural balance is disrupted, Candida overgrowth can occur, leading to a yeast infection.
Symptoms include:
- vaginal itching
- burning during urination or sex
- swelling around the vagina
- soreness
- pain during sex
- redness
- rash
A whitish-gray and clumpy discharge from the vagina, sometimes said to look like cottage cheese, is another sign you have a yeast infection.
What to do
For simple yeast infections, your doctor may prescribe a vaginal antifungal cream, ointment, suppository, or oral tablet. Examples include:
- butoconazole
- clotrimazole
- miconazole
- terconazole
- fluconazole
Many of the creams, ointments, and suppositories are also available without a prescription. For severe or complicated yeast infections, your doctor may prescribe a longer course of treatment.
If the infection recurs, your sexual partner may also have a yeast infection. You should use condoms when having sex if you suspect either of you has a yeast infection.
Antibiotics such as tetracycline and doxycycline can cause permanent tooth staining in children whose teeth are still developing. This effect mostly occurs in children who are younger than
It can affect the teeth of the developing baby if a person is taking these antibiotics and is pregnant.
What to do
Ask your doctor if there are other drug options that might work without this side effect.
Serious side effects from antibiotics aren’t common, but they can occur. Some of the main serious side effects include:
Allergic reactions
Allergic reactions are possible with any medication, including antibiotics. Some allergic reactions can be mild, but others can be serious and need medical attention.
If you’re allergic to a certain antibiotic, you’ll have symptoms right after taking the drug. These symptoms can include trouble breathing, hives, and swelling of your tongue and throat.
When to call your doctor
If you have hives, stop taking the drug and call your doctor. If you have swelling or trouble breathing, stop taking the drug and call 911 right away.
Stevens-Johnson syndrome
Stevens-Johnson syndrome (SJS) is a rare, but serious, disorder of the skin and mucous membranes. Mucous membranes are the moist linings of certain parts of your body, such as your nose, mouth, throat, and lungs.
SJS can happen with any medication, including antibiotics. It occurs more often with antibiotics such as beta-lactams and sulfamethoxazole.
Typically, SJS begins with flu-like symptoms, such as a fever or sore throat. These symptoms may be followed by blisters and a painful rash that spreads. Following that, the top layer of your skin can shed. Other symptoms can include:
- hives
- skin pain
- fever
- cough
- swelling of your face or tongue
- pain in your mouth and throat
What to do
You can’t prevent this condition, but you can try to reduce your risk. You’re at increased risk for SJS if you have a weakened immune system, have had SJS in the past, or have a family history of SJS. If any of these apply to you, talk to your doctor before taking an antibiotic.
When to call your doctor
Call 911 or go to the nearest emergency room right away if you have symptoms of SJS.
Blood reactions
Some antibiotics can cause changes to your blood. For example, leukopenia is a decrease in white blood cell count, which can increase susceptibility to infections.
Another change is thrombocytopenia, which is a low level of platelets. This can cause bleeding, bruising, and slowed blood clotting.
Beta-lactam antibiotics and sulfamethoxazole cause these side effects more often than other antibiotics.
What to do
You can’t prevent these reactions. However, if your immune system is weak, discuss it with your doctor before you take an antibiotic, since this can increase your risk.
When to call your doctor
Call your doctor if you have a new infection or one that appears right after taking an antibiotic.
Call 911 or go to the nearest emergency room right away if you:
- have serious bleeding that doesn’t stop
- have bleeding from your rectum
- cough or vomit up a substance like coffee grounds
Heart problems
In rare cases, certain antibiotics can cause heart problems such as an irregular heartbeat or low blood pressure.
The antibiotics most often linked to these side effects include macrolides (including erythromycin and azithromycin) and fluoroquinolones (including ciprofloxacin)
What to do
If you have an existing heart condition, tell your doctor before you start taking any kind of antibiotic. There may be an alternative medication you can try.
When to call your doctor
Call your doctor if you have new or worsening heart pain, an irregular heart rhythm, or trouble breathing. If your symptoms are severe, call 911 or go to the nearest emergency room.
Tendonitis
Tendonitis is inflammation or irritation of a tendon. Antibiotics such as ciprofloxacin have been reported to cause tendonitis or tendon rupture.
Certain people are at increased risk of tendon rupture, such as people who:
- have existing kidney failure
- have had a kidney, heart, or lung transplant
- have had past tendon problems
- are taking steroids
- are older than 60 years
What to do
Talk with your doctor before starting a new antibiotic if you have any of the above risk factors. This information will help your doctor choose the correct antibiotic for you.
When to call your doctor
If you have new or worsening tendon pain after taking your antibiotic, call your doctor. If the pain is severe, go to the nearest emergency room.
Seizures
It’s rare for antibiotics to cause seizures, but it can happen. Seizures are more common with ciprofloxacin, imipenem, and cephalosporin antibiotics such as cefixime and cephalexin.
What to do
If you have epilepsy or a history of seizures, tell your doctor before you start taking any kind of antibiotic. That way, your doctor can choose an antibiotic that won’t make your condition worse or interact with your seizure medications.
When to call your doctor
Call your doctor if you have new seizures or if your seizures get worse when you take an antibiotic.
Different antibiotics may cause different types of side effects. Your personal health conditions can also affect how the drug interacts with your body.
Speak with your doctor before starting any antibiotic medication so they know what existing conditions you have. Some conditions make you more prone to certain side effects. You may be able to take another antibiotic instead or monitor your symptoms closely if you must take the antibiotic for your infection.
If you develop side effects, go back to your doctor for advice. Seek prompt medical care if you experience severe symptoms.