Antibiotics: Types, Uses, and Side Effects

What Are Antibiotics?

Antibiotics are medicines used to treat or prevent bacterial infections, but they do not work against viral infections such as colds or the flu. Most bacteria are actually not harmful to people—in fact, we need many of them to stay healthy. For example, some bacteria live in our intestines and help us digest food. However, some bacteria can cause serious illnesses and even death. When you have a serious infection caused by bacteria, antibiotics can be useful and even life-saving.

Antibiotics are usually prescribed for serious bacterial infections or when the immune system is weakened, though many infections can improve without them. The key to successful treatment is using the right antibiotic correctly and completing the full course, which helps ensure recovery and prevent resistance.

Types of Antibiotics

There are various antibiotics available, and each comes with different brand names depending on the manufacturer. Antibiotics are usually grouped together based on how they work, as each type of antibiotic only works against certain types of bacteria or parasites. This is why different antibiotics are used to treat different types of infection.

The main types of antibiotics include:

• Penicillins – Examples include phenoxymethylpenicillin, flucloxacillin, and amoxicillin.
• Cephalosporins – Examples include cefaclor, cefadroxil, and cefalexin.
• Tetracyclines – Examples include tetracycline, doxycycline, and lymecycline.

As well as the above main types of antibiotics, specialist doctors may prescribe a number of other antibiotics for more uncommon infections such as tuberculosis (TB). This leaflet focuses on antibiotics that may be prescribed in general practice.

How Do Antibiotics Work?

Antibiotics work through different mechanisms to combat bacterial infections. Some antibiotics work by killing bacteria or parasites, often done by interfering with the structure of the cell wall of the bacterium or parasite. Other antibiotics work by stopping bacteria or parasites from multiplying, preventing the infection from spreading further.

Understanding these mechanisms helps explain why different antibiotics are effective against different types of bacteria and why completing the full course is essential for successful treatment.

When Are Antibiotics Usually Prescribed?

Antibiotics are prescribed when there is a confirmed or suspected bacterial infection that requires medical treatment. They are commonly used for serious bacterial infections or when the immune system is compromised, but they should not be used for viral infections.

It is important to note that eighty percent of all antibiotics are prescribed in general practice, with most used for acute cough and respiratory tract infections—even though many of these infections are self-limiting and may improve without antibiotic treatment. Overuse of antibiotics contributes to the growing problem of antimicrobial resistance, which is recognized as a major public health problem.

Which Antibiotic Is Usually Prescribed?

The choice of antibiotic mainly depends on where the infection is and which bacteria is likely causing it. This is because each antibiotic is effective only against certain bacteria and parasites. For example, in pneumonia, the doctor knows what kinds of bacteria typically cause most cases of the disease. He or she will choose the antibiotic that best combats those kinds of bacteria.

Your healthcare provider will consider factors such as the location of the infection, the type of bacteria involved, your medical history, and any known allergies before selecting the most appropriate antibiotic for your condition.

How to Take Antibiotics

Take antibiotics as directed on the packet, or the patient information leaflet that comes with the medicine, or as instructed by your GP or pharmacist.

Antibiotics can come in various forms:

• Tablets, capsules, or liquid – These can be used to treat most types of mild to moderate infections in the body.
• Creams, lotions, sprays, and drops – These are often used to treat skin infections and eye or ear infections.
• Injections – These can be given as an injection or through a drip directly into the blood or muscle, and are used for more serious infections.

It is crucial to follow the prescribed dosage and frequency exactly as directed. Taking antibiotics at the correct times and in the correct amounts ensures that therapeutic levels are maintained in your body, maximizing the effectiveness of the treatment.

Side Effects of Antibiotics

Side effects can include nausea, vomiting, diarrhoea, bloating, and indigestion. Some people can also have an allergic reaction to antibiotics—especially penicillin. Most side effects are mild and may resolve on their own as your body adjusts to the medication.

Common side effects by antibiotic type:

• Penicillins and cephalosporins: Allergic reactions (ranging from mild rash to severe anaphylaxis), nausea, vomiting, and diarrhea.
• Tetracyclines: Sensitivity to sunlight, nausea, and photosensitivity reactions.
• Other antibiotics: Vary depending on the specific medication and individual factors.

If you experience severe allergic reactions such as difficulty breathing, swelling of the throat or lips, or severe rash, seek immediate medical attention. Always inform your healthcare provider about any previous allergic reactions to antibiotics before starting treatment.

Interactions

Antibiotics can interact with other medicines you may be taking. These interactions can affect how well the antibiotic works or increase the risk of side effects. It is important to inform your healthcare provider or pharmacist about all medications, supplements, and herbal remedies you are currently taking before starting antibiotic treatment.

Some antibiotics may interfere with:

• Oral contraceptives (birth control pills)
• Blood thinners
• Certain heart medications
• Other antibiotics

Your pharmacist can review all your medications and alert you to any potential interactions before you begin taking antibiotics.

How to Get Antibiotics

Antibiotics are prescription medicines in most countries and cannot be purchased over-the-counter without a valid prescription from a healthcare provider. To obtain antibiotics, you must:

• Consult with your GP or other healthcare provider about your symptoms
• Receive a medical evaluation and diagnosis
• Obtain a prescription if antibiotics are deemed necessary
• Fill the prescription at a pharmacy

Your healthcare provider will determine whether antibiotics are appropriate for your condition and, if so, which specific antibiotic is most suitable.

How Long Do You Take Antibiotics For?

A full course of antibiotics should always be taken, even if you feel better early. The length of treatment depends on the type of infection, the antibiotic prescribed, and individual factors such as your age and overall health.

Completing the full course is essential because:

• It ensures all bacteria are eliminated from your body
• It prevents the infection from returning
• It helps prevent antibiotic resistance by ensuring bacteria are completely eradicated
• It reduces the risk of complications

Even if your symptoms improve before the course is finished, continuing to take the medication as prescribed is crucial for successful treatment. Stopping early can allow surviving bacteria to multiply and develop resistance to the antibiotic.

Who Cannot Take Antibiotics?

Certain groups of people need special consideration when taking antibiotics:

• People with known allergies – Those with documented allergies to specific antibiotics should avoid those medications and inform their healthcare provider of all known allergies.
• Pregnant and breastfeeding women – Some antibiotics are not safe during pregnancy or breastfeeding, though some are considered safe. Always consult with your healthcare provider.
• People with liver or kidney disease – Certain antibiotics may need dose adjustments or should be avoided entirely.
• People taking certain other medications – Some drug interactions may preclude the use of specific antibiotics.
• Infants and very young children – Some antibiotics are not appropriate for young children.

Always discuss your medical history, current medications, and any allergies with your healthcare provider before starting antibiotic treatment.

Frequently Asked Questions

Q: Why don’t antibiotics work for colds and flu?

A: Colds and flu are caused by viruses, not bacteria. Antibiotics are designed to kill bacteria or prevent them from multiplying, so they have no effect on viral infections. Antiviral medications are used instead for some viral infections.

Q: What is antibiotic resistance?

A: Antibiotic resistance occurs when bacteria develop the ability to survive and multiply despite the presence of antibiotics that previously killed them. This happens when antibiotics are overused or not taken properly. Using antibiotics when not needed or not completing the full course can accelerate the development of antibiotic-resistant bacteria.

Q: Can I stop taking antibiotics when I feel better?

A: No. You should always complete the full course of antibiotics as prescribed, even if symptoms improve. Stopping early allows remaining bacteria to survive and potentially develop resistance.

Q: Are there ways to reduce unnecessary antibiotic use?

A: Yes. Patient education about when antibiotics are appropriate and when they are not can significantly reduce unnecessary prescriptions. Following your healthcare provider’s advice, using antibiotics only when prescribed for bacterial infections, and completing the full course all help combat antibiotic resistance.

Q: What should I do if I experience an allergic reaction to antibiotics?

A: If you experience symptoms of an allergic reaction—such as rash, itching, swelling, or difficulty breathing—contact your healthcare provider or emergency services immediately. Always inform healthcare providers about antibiotic allergies before starting treatment.

Q: Can antibiotics interact with other medications?

A: Yes, antibiotics can interact with other medicines. Always inform your healthcare provider and pharmacist about all medications and supplements you are taking before starting antibiotic treatment.

Q: How should I store antibiotics?

A: Store antibiotics according to the instructions on the package or leaflet. Most should be stored at room temperature, away from moisture and heat. Some liquid antibiotics require refrigeration. Always keep antibiotics in their original container with the label intact.

Key Points to Remember

• Antibiotics treat bacterial infections but do not work against viruses.
• Always complete the full course of antibiotics as prescribed.
• Different antibiotics work against different bacteria, so the right choice depends on the type of infection.
• Follow dosage instructions exactly as directed by your healthcare provider or pharmacist.
• Inform your healthcare provider about allergies and other medications before starting antibiotics.
• Side effects are usually mild but should be reported to your healthcare provider.
• Do not share antibiotics with others, even if they have similar symptoms.
• Proper antibiotic use helps prevent the serious problem of antibiotic resistance.

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Author

Sneha TeteBeauty & Lifestyle Writer

 

Sneha is a relationships and lifestyle writer with a strong foundation in applied linguistics and certified training in relationship coaching. She brings over five years of writing experience to renewcure,  crafting thoughtful, research-driven content that empowers readers to build healthier relationships, boost emotional well-being, and embrace holistic living.

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