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Antibiotics are types of medicines that fight certain infections and can save lives if taken as directed by your doctor. This medicine can stop the growth of bacteria or destroy them.

Before bacteria can multiply and cause symptoms of certain diseases, your immune system is designed to kill them. White blood cells (leukocytes) attack harmful bacteria and even if symptoms appear, your immune system can usually fight off the infections.

However, sometimes the harmful bacteria can come in excessive amounts and your immune system cannot fight them all – this is where antibiotics play a key role. The first of its kind is penicillin. Penicillin-based antibiotics, such as ampicillin, amoxicillin, and penicillin G, are still available to treat a variety of infections and have been around for a long time.

Several types of modern antibiotics are also available and only prescribed by doctors. Topical antibiotics are available in the form of creams and ointments. 

Types of Antibiotics

1. Penicillins

Penicillins contain five groups of antibiotics such as aminopenicillins, antipseudomonal penicillins, beta-lactamase inhibitors, natural penicillins, and penicillinase-resistant penicillins:

2. Tetracyclines

Tetracyclines are broad-spectrum antibiotics that fight many bacteria and treat conditions such as acne, urinary tract infections (UTIs), intestinal tract infections, eye infections, sexually transmitted diseases, periodontitis (gum disease), and other bacterial infections.

3. Cephalosporins

Cephalosporins treat many types of infections, such as strep throat, ear infections, urinary tract infections, skin infections, lung infections, and meningitis.

4. Quinolone

Quinolone is also known as fluoroquinolone, which can be used to treat urinary tract infections if other options do not work effectively, hospital-acquired pneumonia, bacterial prostatitis, and anthrax or plague.

5. Lincomycins

Lincomycins can be used for serious infections, such as pelvic inflammatory disease, intra-abdominal infections, lower respiratory tract infections, or bone and joint infections. Some forms of lincomycin are topically applied for acne.

6. Macrolides

Macrolides can be used to treat pneumonia, pertussis (whooping cough), or minor skin infections. Ketolides is a new generation of antibiotics, which developed to overcome the resistance of macrolide bacteria.

7. Sulfonamides

Sulfonamides are effective in treating urinary tract infections (UTIs), treatment or prevention of pneumocystis pneumonia (PCP), or ear infections (otitis media).

8. Antibiotic Glycopeptide

This type of antibiotic can be used to treat methicillin-resistant staphylococcus aureus (MRSA) infections, severe skin infections, and enterococcal infections such as endocarditis–which are resistant to beta-lactam and other antibiotics.

9. Aminoglycosides

This medicine is usually given intravenously. 

10. Carbapenem

These injectable beta-lactam antibiotics have a broad spectrum and can be used to treat life-threatening bacterial infections, such as stomach infections, pneumonia, kidney infections, and many other serious types of bacteria.

Guidelines for Antibiotics

  • Antibiotics can usually be taken by mouth, but your doctor may insert them through injection or apply them directly to infected parts of the body.
  • Most antibiotics begin to combat infection within a few hours. You should complete the entire treatment to prevent the return of the infection.
  • Stopping treatment before it is completely healed can increase the risk of bacteria becoming immune to future treatments. Surviving bacteria will be exposed to antibiotics and develop antibiotics resistance.
  • You need to complete the treatment, even after your symptoms have improved.
  • You should not take antibiotics with certain foods and drinks. Take it on an empty stomach, about an hour before meals, or 2 hours afterwards. Follow the instructions properly to get the most benefits of the medicine. You should not drink alcohol if you take metronidazole.
  • Avoid dairy products when consuming tetracyclines, as such products can interfere with their absorption.

How are Antibiotics Used

Your doctor may prescribe antibiotics if you have bacterial infections and other medicines are not effective to fight against viruses. Find out if your infection is caused by bacteria or viruses to get proper treatment. The virus causes most upper respiratory tract infections (ISPA), but antibiotics do not work against this type of virus.

If people overuse antibiotics or use them improperly, bacteria may become immune. This means it becomes less effective against these types of bacteria, as they are able to strengthen their defences.

Your doctor may also prescribe broad-spectrum antibiotics to treat a wide variety of infections. While narrow-spectrum antibiotics are only effective against some types of bacteria.

Some antibiotics attack aerobic bacteria, while others work against anaerobic bacteria. Aerobic bacteria require oxygen, while anaerobic bacteria do not.

In some cases, antibiotics are administered to prevent rather than treat infections–as what may occur before surgery, such as prophylactic antibiotics.

Contraindications for Antibiotics

Most bacteria that live in your body are harmless. However, bacteria can infect almost any organs. The good thing is that antibiotics can help prevent and stop the growth of bacteria within your body.

Only bacterial infections can be killed with antibiotics. Colds, flu, certain types of cough, certain bronchitis infections, certain types of sore throat, and stomach flu are caused by viruses. Antibiotics will not work to treat the diseases. Your doctor will likely ask you to wait for you to recover or prescribe antiviral medications to heal your condition. 

It is unclear if your infection is caused by a virus or bacteria. Sometimes your doctor may likely perform a test before deciding the right treatment for your condition.

Some antibiotics may work on different types of bacteria or known as broad-spectrum antibiotics, while narrow-spectrum antibiotics only target certain bacteria

Antibiotic Drug Interactions

You should not take other medications or other herbal remedies without talking to your doctor first. Certain medicines may also interact with antibiotics.

Some doctors suggest that antibiotics may reduce the effectiveness of oral contraceptives. However, it requires further research to back up this statement. 

Common Antibiotics Side Effects

Antibiotics may usually cause the following side effects:

  • Nausea
  • Diarrhea
  • Gag
  • Stomach ache
  • Red rash on your skin
  • Certain antibiotics or long-term use, possible side effects may include yeast infection affecting your mouth, digestive tract, and vagina.

There are less common side effects of antibiotics, such as: 

  • Blood disorders – when taking trimethoprim.
  • Deafness – when taking erythromycin and aminoglycosides.
  • Formation of kidney stones – when taking sulfonamides.
  • Abnormal blood clots – when taking cephalosporins.
  • Sunlight sensitivity – when taking tetracyclines.

Some people, especially older adults, may experience inflammatory bowel disease that can lead to severe bloody diarrhea. In less common cases, penicillins, cephalosporins, and erythromycin can also cause colitis.

Allergy Risk Factors

Some people may experience allergic reactions to antibiotics, particularly penicillin. Side effects may include a red rash, swollen tongue and face, or difficulty breathing.

Antibiotic allergy may occur in the form of immediate or delayed hypersensitivity reactions. Inform your doctor or pharmacist if you have antibiotic allergy. Reactions to antibiotics can be serious and sometimes fatal or known as anaphylaxis.

People with liver or kidney function problems should be cautious before taking antibiotics–as it can affect the type of antibiotics or the recommended dosage.

Moreover, if you are pregnant or nursing mother, be sure to consult your doctor about which type of antibiotic to take.


Make an appointment with your doctor or pharmacist through Smarter Health to find out more about the recommended dosage for antibiotics and its proper use based on your condition Smarter Health allows you to access health services whenever you need them.

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