Side Effects Of Antibiotics: 10 Common Ones You Need To Know

side effects of antibiotics

Antibiotics are often lifesavers for us when nothing else works. Unfortunately, their use is not without side effects – some serious enough to warrant attention. While a little nausea or reversible tooth discoloration may not be worrisome, long-term impact on your immunity or the chance of developing antibiotic resistance are.

Here’s the lowdown on the side effects of antibiotic use and what the fine print on the labels really means for you.


1. Digestive System Problems

According to the National Health Service, UK, 1 in 10 people who take antibiotics experience complaints surrounding the digestive system. These include nausea, vomiting, diarrhea, indigestion, and bloating. A loss of appetite may be another side effect. You may also have some form of abdominal pain. Typically such side effects are mild and settle down on their own once the course of medication is completed. In case you experience very severe forms of these problems or the issues persist even after you are done taking the full course of antibiotics, you need to reach out to your doctor as soon as possible.1

2. Adverse Impact On Immunity

An issue with antibiotic use that has come into focus in recent years is the impact of these medicines on the balance of microbiota in the gut. Your immune system relies heavily on the balance between good bacteria and pathogenic microbes that cause illness. In a normal healthy intestine or gut, the good bacteria outnumber the bad, enabling the body to fight off infections. However, improper or prolonged use of antibiotics can throw this careful balance, killing off good bacteria along with the bad and making you more susceptible to infections.2


3. Increased Risk Of Metabolic Disorders

Research has found that the composition of gut microbiota plays a critical role in inflammatory and autoimmune disorders. Which is why exposure to antibiotics has been connected to metabolic disorders that include obesity, diabetes, and metabolic syndrome. The disrupted balance in microbiota results in chronic low-grade inflammation, which in turn has been linked to excess fat accumulation. This obesity could gradually inch towards full blown metabolic syndrome. And if that happens, you are at greater risk of type 2 diabetes, fatty liver disease, and cardiovascular disease, among other things.3

4. Type 1 Diabetes Risk

The incidence of insulin-dependent type 1 diabetes in industrialized nations has been on the rise over the past few decades. Researchers believe there may be a connection between antibiotic use and this autoimmune disease.4 Separate research has also found that while a single course of antibiotic use did not increase diabetes risk, when a patient was given two to five such courses there was an increased risk of diabetes for certain antibiotics including penicillin, quinolones, macrolides, and cephalosporins.5


5. Vaginal Yeast Infections

Just as antibiotics meddle with the balance of gut flora, they also interfere with flora balance of the vagina. This may allow certain fungal species like Candida albicans (normally present only in very small amounts in the area) to thrive when there are less “good bacteria” to compete with as a result of taking antibiotics. Animal studies have proven this effect.6 Which is why healthcare experts suggest taking Lactobacillus acidophilus tablets or eating yogurt with live cultures when you are on a course of antibiotics. This can help with keeping the balance of good bacteria and may help you avoid a yeast infection.7

6. Mouth Sores, Ulcers, And Blisters

For similar reasons that you develop vaginal yeast infections, you could also develop mouth sores due to oral thrush or candidiasis.8 Mouth ulcers or blisters may also result from using antibiotics.9 Some medicines like amoxicillin are often cited as having this side effect.


7. Tooth Discoloration

The use of tetracycline and beta-lactam antibiotics has been seen to cause tooth discoloration. If tetracycline is used when teeth are developing, as in the case of infants or children aged 8 and under the discoloration is intrinsic and permanent. It can even affect a baby in the womb in the second half of your pregnancy. With beta-lactam and tetracycline use at other times, the discoloration is superficial, extrinsic, and reversible. You can have your teeth professionally cleaned or brush carefully to reverse the discoloration.10

8. Allergies: Skin Rashes, Coughs, Wheezing, And Breathing Difficulty

Allergic reactions to antibiotics occur in about 1 in 15 cases. Certain antibiotics like cephalosporins and penicillin are more common offenders. If you do have an allergic reaction, you may experience hives or raised skin rash that can be quite itchy. Other symptoms of an allergy are wheezing or coughing. Some people may feel a tightness in their throat that can interfere with breathing. If this becomes severe, you must rush to the hospital for emergency medical care. How can you tell if your reaction is severe? If there’s a sense of dread or fear, a sudden dip in blood pressure, confusion and light-headedness, rapid heartbeat, or loss of consciousness, you are experiencing anaphylaxis, a very severe allergic reaction. For most people, though, reactions are mild to moderate and antihistamines can help overcome the side effects.11


9. Antibiotic Resistance

Antibiotic overuse or improper use can result in antibiotic resistance, a problem that has the global medical community concerned. The result is antibiotic-resistant strains of bacteria that become increasingly difficult and expensive to kill or overcome as they are able to resist the action of the medicine or reduce their effectiveness. It could even result in long-term disability or death.12

10. Side Effects Specific To You

In addition to these broad effects of antibiotic use, there may be additional side effects that impact some of us. To know what these are, read the labels or find out more about the specific antibiotic you have been prescribed. For instance, tetracyclines can make you sensitive to light both natural and artificial. If this happens to you, you will need to avoid too much light exposure – especially to bright light.13


Other side effects like the fluoroquinolone-induced tendinopathy (an inflammation of the tendons) need further investigation as some believe the risk is negligible, while others feel there is a direct connection. The FDA, however, has said there is adequate data to suggest the need for caution while using fluoroquinolone antibiotics in a subset of the population. As such, you should check whether you are cleared for use by sharing a complete medical history with the doctor who is examining you.14

To rule out any drug interactions with the medication you already take, discuss your regimen with your doctor before taking antibiotics. They may inhibit the action of the other medication or prevent them from working.