What is the Difference Between Doxycycline and Tetracycline?

Doxycycline and tetracycline are both antibiotics used to treat various infections, but they have some differences in their absorption, side effects, and potential hepatotoxicity. Here are the main differences between the two:

1. Absorption: Doxycycline is better absorbed and reaches peak serum concentrations more quickly than tetracycline, but the difference is not large. Both drugs can be taken on an empty stomach but should be taken with food if there is gastrointestinal irritation as a result.
2. Side Effects: Both doxycycline and tetracycline have similar side effects, including diarrhea or loose stools, nausea, abdominal pain, vomiting, discoloration of teeth if used in patients below 8 years of age, and exaggerated sunburn (photosensitivity). However, tetracycline has additional side effects such as rash, headache, and dizziness.
3. Hepatotoxicity: Doxycycline was found to be potentially less hepatotoxic than tetracycline in a population-based case-control study. The study suggested that doxycycline could potentially be a safe substitute for tetracycline when appropriate.
4. Indications: Doxycycline and tetracycline are both used to treat various infections, including respiratory tract infections due to Hemophilus influenzae, Streptococcus pneumoniae, or Mycoplasma pneumoniae. Doxycycline is also used for malaria prophylaxis and is effective in controlling non-infectious, inflammatory skin and mucosal diseases. Tetracycline is used for infections of the respiratory tract, urinary tract, and skin; urethritis, typhus, Rocky Mountain spotted fever, certain sexually transmitted diseases (STDs), acne, anthrax, cholera, and H. pylori.

In summary, doxycycline and tetracycline are both antibiotics with similar uses but differ in their absorption, side effects, and potential hepatotoxicity. Doxycycline is better absorbed and has fewer side effects compared to tetracycline, making it a potentially safer option when appropriate.

Comparative Table: Doxycycline vs Tetracycline

Doxycycline and tetracycline are both antibiotics belonging to the tetracycline antibiotic class, but they have some differences in their structures, the infections they can treat, and their side effects. Here is a table comparing the differences between doxycycline and tetracycline:

Both antibiotics work by inhibiting bacterial production of proteins, rendering the bacteria unable to function. However, doxycycline is sometimes used as a prevention for malaria, while tetracycline is not. It is essential to discuss taking an antibiotic with your doctor to ensure your safety and consider any medications and health conditions that may interact with the antibiotics.