Antibiotics: Groups or Classes, Side Effects, Do Antibiotics Treat Viral Infections & Fungal Infections Also?

What are Antibiotics?

Antibiotics are prescription drugs that help cure infections caused by bacteria. Some of the more common infections treated with antibiotics include bronchitis, pneumonia and urinary tract infections. Antibiotics work by killing the bacteria causing the infection or by ceasing the bacteria from growing and multiplying.

What are Antibiotics?

What Are The Different Groups/Classes Of Antibiotics?

There are many different groups or strata of antibiotics. All of these strata have side effects, which affect men and women in the same way. However, certain side effects are more common in some antibiotics than in others.

Although there are more or less over 100 antibiotics, the majority come from only a few types of drugs. These are the main classes of antibiotics:

  • Penicillin’s, such as penicillin and amoxicillin.
  • Cephalosporin’s, such as cephalexin (Keflex).
  • Macrolides, such as erythromycin (E-Mycin), clarithromycin (Biaxin) and azithromycin (Zithromax).
  • Fluoroquinolones, such as ciprofloxacin (Cipro), levofloxacin (Levaquin) and ofloxacin (Floxin).
  • Sulfonamides, such as co-trimoxazole (Bactrim) and trimethoprim (Proloprim).
  • Tetracycline’s, such as tetracycline (Sumycin, Panmycin) and doxycycline (Vibramycin).
  • Aminoglycosides, such as gentamicin (Garamycin) and tobramycin (Tobrex).

Names of Antibiotics

Most antibiotics have two names, the trade or brand name, created by the drug company that manufactures the drug, and a generic name, based on the antibiotic’s chemical structure or chemical class. Trade names such as Keflex and Zithromax are capitalized. Generics such as cephalexin and azithromycin are not capitalized.

Can Antibiotics Be Prescribed For Everyone And Every Infection?

Each antibiotic is effective only for certain types of infections; and a doctor is best able to compare your needs with the available medicines. Also, a person may have allergies that eliminate a class of antibiotic from prescription, such as a penicillin allergy preventing your doctor from prescribing amoxicillin.

How To Decide Which Antibiotic To Prescribe?

In most cases of antibiotic use, a doctor must choose an antibiotic based on the most likely cause of the infection. For example, if you have an earache, the doctor knows what kinds of bacteria cause most ear infections. He or she will choose the antibiotic that best fights against those kinds of bacteria. In another example, a few bacteria cause most cases of pneumonia. If you are diagnosed with pneumonia, the doctor will choose an antibiotic that will combat these bacteria which have caused pneumonia.
Other factors may be considered when choosing an antibiotic. Medication cost, dosing schedule, and common side effects are often taken into account. Patterns of infection in your community may also be considered before deciding on an antibiotic.

In some cases, laboratory tests may be used to help a doctor choose an antibiotic. Special strains of the bacteria, such as Gram stains, can be used to identify bacteria under the microscope and may help narrow down which species of bacteria is causing infection. Certain bacterial species will take a stain and others will not.

Do Antibiotics Treat Viral Infections & Fungal Infections Also?

Although antibiotics are useful in a wide variety of infections, it is important to realize that antibiotics only treat bacterial infections. Antibiotics are futile against viral infections (for example, the common cold) and fungal infections (such as ringworm). Your doctor can best determine if an antibiotic is right for your condition. Antibiotics, however, can be prescribed in these conditions to prevent a secondary bacterial infection.

What are the Symptoms of an Allergic Reaction to an Antibiotic?

Some people are allergic to certain types of antibiotics. The most common antibiotic allergy people have is to penicillin. If you have a question about a potential allergy to antibiotic, ask your doctor or pharmacist before taking the medicine.

Allergic reactions to any antibiotic commonly have the following symptoms:

What are the Side Effects of Antibiotic?

Common side effects of Antibiotics are:

Stomach Upset from an Antibiotic

These antibiotic side effects include nausea, vomiting, cramps and diarrhea. Macrolide antibiotics, cephalosporins, penicillins, and fluoroquinolones may cause more stomach upset than other antibiotics.

Photosensitivity from an Antibiotic

If you’re taking an antibiotic, such as tetracycline, your body can become more sensitive to light. This side effect from antibiotics can make the light seem brighter in your eyes. It can also make your skin more prone to sunburn. Photosensitivity should go away after you finish taking the antibiotic. Although in some cases, it can persist for a long time even after the medication has stopped.

In order to prevent this to the most possible extent, when you know you’ll be out in the sun, take certain precautions to stay safe and comfortable. Be sure to 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 to reduce the photosensitivity side effects from antibiotic.

Fever from an Antibiotic

Fevers are a common side effect of many medications, including antibiotics. A fever may happen because of an allergic reaction to a medication or as a bad side effect. Drug fevers can occur with any antibiotic, but they’re more common with beta-lactams, cephalexin, minocycline and sulfonamides.

If you get a fever while taking an antibiotic, it is likely to go away on its own. If your fever doesn’t go away after 24-48 hours, consult your doctor or pharmacist about using over-the-counter medications, such as Tylenol or Motrin to help bring down your fever. But if you have a fever greater than 100.4°F, a skin rash or trouble breathing, then call your doctor or 911 right away.

Tooth Discoloration from an Antibiotic

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 8 years. Also, if a pregnant woman takes these drugs, they may stain the developing child’s primary teeth. Ask your doctor why they’re prescribing one of these antibiotics for you (if you’re pregnant) or your child. Also ask if there are other antibiotic options that might work and won’t have this side effect.

What are the Serious Side Effects of Antibiotics?

Serious side effects from antibiotics aren’t common, but they can occur. Some of the primary serious side effects from antibiotics include:

Allergic Reaction from an Antibiotic

Allergic reactions can happen 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. If you have hives, stop taking the antibiotic and call your doctor. If you have swelling or trouble breathing, stop taking the drug and go to a hospital right away.

Stevens-Johnson Syndrome from an Antibiotic

Stevens-Johnson syndrome (SJS) is a rare, but serious disorder of your skin and mucous membranes. It’s a reaction that might occur with any medication, including antibiotics. It occurs more often with antibiotics, such as beta-lactams and sulfamethoxazole. Mostly, SJS begins with flu-like symptoms, such as a fever or sore throat. These symptoms may be followed by a painful rash that spreads. Blisters might also happen. Following that, the top layer of your skin can shed.

Other symptoms include: hives, skin pain, fever, cough, swelling of your face or tongue and pain in your mouth and throat. You can’t totally prevent this condition, but you can try to reduce your risk. You’re at increased risk for SJS in certain cases, such as if you have a weakened immune system, have had SJS in the past, or have a family history of SJS. If you believe any of these conditions apply to you, talk to your doctor before taking an antibiotic.

Blood Reactions from an Antibiotic

Some antibiotics can cause changes to your blood. For example, leucopenia is a decrease in the number of white blood cells, which can lead to increased infections. Another change blood reaction to an antibiotic is thrombocytopenia, which is a low level of platelets. This effect can cause bleeding, bruising, and slow blood clotting. Beta-lactam antibiotics and sulfamethoxazole cause these side effects more often than others. You can’t prevent these reactions. However, you’re at higher risk of them if you have a weakened immune system. If your immune system is weak, then discuss it with your doctor before you take an antibiotic.

When To Consult Your Doctor

Call your doctor if you have a new infection or one that appears immediately after taking an antibiotic. Go to the nearest emergency room right away if you:

  • Have serious bleeding that does not stop.
  • Have bleeding from your rectum.
  • Cough up a substance like coffee grounds.

Heart Problems from an Antibiotic

In very few cases, certain antibiotics can cause heart problems, such as an irregular heartbeat or low blood pressure. The antibiotics most often related with these side effects are erythromycin and some fluoroquinolones, such as ciprofloxacin. The antifungal terbinafine can also cause heart problem. If you have an existing heart condition, be sure to tell your doctor before you start taking any kind of antibiotic.

This information will help your doctor choose the right antibiotic for you. Call your doctor if you have new heartache or your previous heart pain aggravates, an irregular heart rhythm, or trouble breathing. If your symptoms are severe, go to the nearest emergency room.

Tendonitis from an Antibiotic

Tendonitis is inflammation or irritation of a tendon. Tendons are thick cords that attach bone to muscle, and they can be found throughout your body. Antibiotics, such as ciprofloxacin have been said to cause tendonitis or tendon rupture. This is when the tendon tears or rips apart. All people are at risk for tendon problems when taking certain antibiotics. However, certain people are at increased risk of tendon rupture. These include people who:

  • Have existing kidney failure.
  • Have had a kidney, heart or lung transplant.
  • Have past tendon problems.
  • Are taking steroids.
  • Are older than 60 years.

Talk to your doctor before starting a new antibiotic if you experience any of the aforementioned risk factors. This information will help your doctor choose the correct antibiotic for you. If you have new or exacerbated tendon pain after taking your antibiotic, call your doctor. If the pain is severe, go to the nearest emergency room.

Seizures from an Antibiotic

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. If you have epilepsy or a history of seizures, be sure to 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 aggravate or interfere with your seizure medication. Call your doctor if you have new seizures or your seizures get worse when you take an antibiotic.

Do You Need To Take Antibiotics with Food?

Ask your doctor or pharmacist if you can take your antibiotic with food. Eating can help lessen stomach side effects from certain antibiotics, such as amoxicillin and doxycycline. However, this approach does not work for all the antibiotics. Some antibiotics, such as tetracycline, have to 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 reduce or avoid stomach side effects with a particular antibiotic.

Antibiotics: Points To Bear In Mind

Always keep in mind a few points while you take your antibiotics. Be smart about using antibiotics. Keep in mind the fact that antibiotics can help cure infections caused by bacteria, but not infections caused by viruses or any other organism. Here are some things you can do to help make sure antibiotics will work when you need them:

  • Always ask your doctor if antibiotics are the best treatment. Explain that you do not want antibiotics unless you need them.
  • Avoid pressuring your doctor into prescribing antibiotics when they won’t help you feel better or cure your illness. Ask your doctor what else you can do to feel better.
  • Do not use antibiotics that were prescribed for a different illness or for someone else. You may delay correct treatment and your condition might worsen.
  • Protect yourself from illnesses. Keep your hands clean by washing them well with soap and clean, running water. Maintain a proper diet.
  • Get a flu vaccine and other vaccines when you need them.

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:April 4, 2019

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