What are the common doxycycline side effects?

Posted on  April 6, 2021, Edited by Jason, Category  

What is doxycycline?

1. Definition

Doxycycline is a kind of tetracyclines, which can treat Mycoplasma chlamydia infection. It is pale yellow or yellow crystalline powder, smelly and bitter. It is easily soluble in water and methanol, slightly soluble in ethanol and acetone, and insoluble in chloroform.

Doxycycline is a special type of antibiotic that can kill a variety of pathogenic microorganisms that are difficult to be killed by other antibiotics, including bacteria and parasites. Parasites can colonize cells as intracellular organisms for a long time, thereby it is difficult to be killed by many antibiotics. But doxycycline side effects are not things we should overlook.

Unlike other types of antibiotics, doxycycline can penetrate into tissues and eventually enter cells, where the antibiotic can kill pathogens. A variety of intracellular organisms that are sensitive to doxycycline include many pathogens that cause zoonotic diseases, chlamydia, legionella, and plasmodium. Other susceptible microorganisms include spirochetes and acne-causing bacteria, Bacillus anthracis, and Vibrio cholerae.

2. Function

Its antibacterial spectrum is basically the same as that of tetracycline and oxytetracycline, and the antibacterial power in vivo and in vitro is stronger than that of tetracycline. Microorganisms have close cross-resistance to doxycycline, tetracycline and oxytetracycline.

It is mainly used for upper respiratory tract infections, tonsillitis, biliary tract infections, lymphadenitis, cellulitis, chronic bronchitis, etc. caused by sensitive gram-positive bacteria and gram-negative bacilli. It is also used to treat typhus, Tsutsugamushi, mycoplasma pneumonia, etc. It can still be used to treat cholera, and prevent falciparum malaria and Leptospira infection.

3. Traits

Doxycycline hydrochloride is commonly used, which is light yellow or yellow crystalline powder; smelly and bitter. It is easily soluble in water and methanol, slightly soluble in ethanol and acetone, and insoluble in chloroform. Some synthetic drugs containing doxycycline are prone to complex reaction with metal ions in water, forming a red solution and reducing the efficacy.

4. Mechanism of Action

Doxycycline can interfere with the ability of microbial organisms to produce proteins. Proteins are the basic structural elements of life. The production of proteins in cells is usually done in ribosomes, and this process is necessary for the survival of every organism. Doxycycline kills bacteria and parasites, but has no effect on our own cells. The reason is that the human organism has a ribosomal structure completely different from that of simple organisms.

Doxycycline Uses


1. Indications

It is mainly used to treat respiratory, urinary and biliary infections caused by sensitive bacteria. The antibacterial spectrum is basically the same as that of tetracycline and oxytetracycline, and the antibacterial power is stronger than that of tetracycline. Microorganisms have close cross-resistance to doxycycline, tetracycline and oxytetracycline. It is also used for the treatment of typhus, Qiang trypanosomiasis, mycoplasma pneumonia, etc.

In the long-term treatment practice, it has been found that doxycycline is a good antibacterial drug. It is a long-acting and broad-spectrum semi-synthetic tetracycline antibiotic made from oxytetracycline. The reason why doxycycline used to treat chronic bronchitis works well is:

  • Broad antibacterial spectrum and strong antibacterial effect. In addition to having an effect on Gram-positive and negative bacteria, it can also inhibit Rickettsia, Mycoplasma pneumoniae, Chlamydia trachomatis, Amoeba, etc. Especially the common bacteria in the respiratory tract of patients with chronic bronchitis are very sensitive to doxycycline.
  • The effect can be maintained for a long time, and the absorption is fast after oral administration. The maximum effect can be exerted after 3 hours. It is mainly excreted slowly by the kidneys. Adults take 200 mg once orally, and excrete 32% within 24 hours and 41% within 48 hours. The drug concentration is longer than tetracycline and oxytetracycline, which is more suitable for the treatment of chronic inflammation. The oral dose is 0.2 grams on the first day, and then once a day, 0.1 grams (100 mg) each time.

2. Uses

Because doxycycline can kill a series of bacteria that affect the respiratory system of the body, it is usually used to treat pneumonia and bronchitis. At the same time, this antibiotic is also widely used to treat doxycycline acne and urogenital infections. Doxycycline is usually given as a capsule or tablet orally, but sometimes it is also given by intravenous injection. After taking doxycycline, it will exert effect for some time, which means that the drug can be used not only as a therapy, but also as a preventive therapy for body diseases.

Nowadays, doxycycline is widely used by tourists or military personnel to tropical countries to prevent some diseases, such as protecting individuals from malaria parasite infection.  Doxycycline can also provide protection against common bacteria that cause diarrhea. In order to effectively prevent infection, when patients are at risk of disease, they need to take drugs every day.

Doxycycline is able to actively resist a list of pathogenic bacteria used in bacterial warfare, including Bacillus anthracis. So this drug can be used as an effective preventive method to protect individuals from the risk of bacterial warfare or the risks caused by terrorists releasing bacillus anthracis.

3. Veterinary uses

  • Bacterial diseases: often in the respiratory tract, such as pleuropneumonia, swine pneumonia and other diseases. Doxycycline + florfenicol + anti-fever drugs are effective;
  • Actinomycetes: pustules that can grow in various places on pigs. In addition to Streptococcus pyogenes, actinomycetes can also cause this disease. Generally, doxycycline is more effective.
  • "body" disease: Mycoplasma is asthmatic disease, doxycycline + florfenicol (mycoplasma) are effective;
  • Chlamydia: It may be due to sow abortion and the pearl shape of the placenta should be considered, and doxycycline would be great; Or it may be resulted from conjunctivitis, the tetracycline eye drops are better;
  • Spirochetes (swine dysentery, etc.) and Rickettsia are less used, so I won't say more;
  • In Blood protozoa, which is what we often call eperythria and other diseases, doxycycline administration would be fine;
  • Oxytetracycline is generally used in prevention and treatment of sows, with less damage and more easing effects; doxycycline is often used in suckling piglets born after seven days.

4. Development

The development of doxycycline is based on scientists' discovery of penicillin, which is a compound naturally produced from a special mold. Many pharmaceutical companies have begun to investigate the mechanisms and properties of many natural compounds to kill microorganisms, such as those produced by other microorganisms and plants. This process is called bio-discovery. These natural compounds can carry a certain antibacterial activity, and later synthetic modified compounds can often improve the current natural compounds.

Like many antibiotics, doxycycline is very sensitive to antibiotic-resistant bacteria, and there is evidence that this susceptibility has begun to appear in many diseases where doxycycline is widely used, such as the treatment of acne. This means that the use of doxycycline should be reduced or in some cases replaced by some alternative drugs. Of course, scientists need to conduct more in-depth research and exploration in the later stage to find new alternatives.

Doxycycline side effects


1. Adverse Reactions

  • Gastrointestinal reactions are common (about 20%), such as nausea, vomiting, diarrhea, etc., which can be relieved by taking medicine after meals.
  • In patients with mild liver and kidney dysfunction, the half-life of this medicine is not significantly different from that in normal patients, but it should be used with caution in patients with severe liver and kidney dysfunction.
  • Double infection (after long-term use of broad-spectrum antibiotics, the growth of sensitive strains is inhibited, and insensitive strains multiply in large numbers, thereby causing new infections. This is called double infection.)
  • Affect the development of teeth and bones: mainly for the fetus and infants. Tetracycline antibiotics can deposit in the bones and teeth of embryos and young children, and combine with calcium, which can cause yellowing of tooth enamel (commonly known as tetracycline teeth) And hypoplasia.
  • Liver toxicity;
  • Phototoxicity;
  • Kidney toxicity,
  • Pseudotumor of the brain;
  • Vestibular reaction;
  • Allergic reactions. It should generally be contraindicated for children under 8 years old, pregnant women and breastfeeding women.

2. Side effects

The most commonly reported side effect of doxycycline is esophageal inflammation or heartburn, which is often very unpleasant for patients, but patients can effectively prevent the side effects caused by doxycycline by drinking large amounts of water. Twenty percent of people who take the drug often have photosensitivity reactions, which is especially serious for travelers who use the drug for malaria prevention in tropical countries.

Doxycycline should not be used in children and pregnant women, it will cause permanent browning of the user's teeth, and it will also have other adverse effects on the bone development of the fetus. Doxycycline can also increase the toxicity of the anti-inflammatory drug-methotrexate.

3. How to avoid the side effects of doxycycline?

  • Make sure to let your doctor know all the medicines and health products you are taking. Mixing certain drugs with doxycycline will intensify their side effects. For example, ibuprofen will increase the sensitivity of the skin to the sun. If you take these two drugs at the same time, you may be sunburned.
  • Take doxycycline after meals or with food. This can minimize adverse reactions such as nausea and nausea.
  • You should lie down at least one hour after taking the medicine, and you should drink more water as directed by your doctor. These methods all help avoid extreme side effects such as esophageal irritation and ulcers. Severe ulcers need to be checked in order to rule out the possibility of esophageal cancer.
  • Unless the doctor advises you to do that, you should avoid taking doxycycline together with other drugs that stimulate the stomach.
  • Avoid prolonged sun exposure. If you really need to go out, you should take appropriate protection measures.
  • Eating food or health products such as yogurt containing lactic acid bacteria can help prevent yeast infections.

Future development of doxycycline

Recently, when scientists disputed the side effects of the anti-malarial drug Mefloquine used in defense forces and refugees, they emphasized the key role doxycycline plays in replacing the drug Mefloquine. Of course, it is now generally believed that mefloquine should be a more effective drug for preventing malaria, but more interestingly, the results of previous studies have shown that many people actually prefer mefloquine to doxycycline. This may reflect the side effects of doxycycline, and because doxycycline needs to be taken every day, it will bring a lot of inconvenience to patients.

Recent studies have found that doxycycline can affect special processes in human cells, especially a class of enzymes that are very important for the body's inflammatory response. This feature may be very beneficial, and it can help researchers develop treatments for many diseases, new treatments for infectious diseases, including cancer (especially bone-related cancers), autoimmune diseases (including rheumatoid arthritis and multiple sclerosis), atherosclerotic diseases (plaques that cause heart disease). However, the application of these new therapies is currently only in the experimental stage. The researchers said that they will continue to explore.


Doxycycline is a tetracycline antibiotic that works well for respiratory infections and can also be brought to tropical countries as a preventive measure to prevent some annoying diseases. Doxycycline side effects exist indeed, but it is still of great significance for human health. The future of doxycycline is promising.

BALLYA provides a ballya-tetracyclines-test to tell you if there are tetracyclines residues in honey, chicken and pork.


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