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Doxycycline: effect, areas of application, side effects

by Josephine Andrews
Published: Last Updated on 258 views

The active ingredient doxycycline is a broad spectrum antibiotic, i.e. an antibiotic that is effective against a large number of different bacteria. Its most important area of ​​application are bacterial infections and associated diseases. In addition, doxycycline is also used against some disease-causing protozoa, such as the pathogen that causes malaria. Here you can read everything you need to know about the effects of doxycycline, side effects and areas of application.

This is how doxycycline works

Doxycycline is an antibiotic from the tetracycline group. Like all other tetracycline derivatives, it has a growth-inhibiting effect on the bacteria , i.e. it is a so-called bacteriostatic active ingredient.

In order to be able to grow, bacteria (like other organisms) have to read the information in their genetic material and use the information obtained to produce proteins that fulfill vital functions in the cell. This reading and translation of the bacterial genetic information is specifically inhibited by tetracyclines such as doxycycline – the growth of the pathogens stops, giving the body the chance to get the infection under control by means of immune reactions.

Human cells are not hindered in their growth by doxycycline, since the antibiotic acts selectively only on protozoa.

When is doxycycline used?

Doxycycline is used to treat various infectious diseases. Examples include bacterial respiratory infections (such as chronic bronchitis , atypical pneumonia , sinusitis , and otitis media ).

The antibiotic can also be administered for Lyme disease , diseases of the urinary tract, the genital tract and the prostate , various gastrointestinal diseases (such as cholera ) and skin diseases (such as rosacea and acne vulgaris).

Another area of ​​application for doxycycline is particularly interesting for long-distance travelers: malaria . In certain travel destinations, the antibiotic is suitable both for the prevention and for the treatment of the tropical disease. Especially in areas where the malaria pathogen is resistant to many different antibiotics, doxycycline is usually administered in combination with one or more other antibiotics.

In Germany, however, there is no preparation with doxycycline that is approved for the treatment of malaria. If a vacationer comes back to Germany with malaria, doxycycline can only be used for treatment “off-label” in this country – i.e. outside of its official approval.

How Doxycycline is used

The dosage and duration of use depend on the type and severity of the disease. The patient should strictly follow the doctor’s instructions.

The duration of treatment with doxycycline in acute infections is often five days to three weeks, since doxycycline as a growth inhibitor of bacteria has a delayed effect compared to bactericidal (bactericidal) antibiotics. Aside from acute infections, doxycycline can also be used over a period of several months (e.g. in the case of the skin disease rosacea).

Doxycycline is usually prescribed perorally, i.e. to be taken in the form of tablets, capsules, prolonged-release capsules (prolonged-release capsules), effervescent tablets or as granules to be made up into a suspension. The usual dosage is 50, 100, or 200 milligrams per single dose.

Doxycycline can be taken once a day or divided into up to three doses (morning, noon, evening). It is recommended that the antibiotic be taken with a meal and a glass of water (no milk or milk products), as the digestive tract then tolerates the active substance better.

It should be taken in an upright position and at approximately the same times each day.

What are the side effects of doxycycline?

Various side effects can occur during treatment with doxycycline. Taking preparations containing doxycycline can lead to irritation and inflammation of the mucous membranes in the mouth and throat. Sometimes there are also complaints of the gastrointestinal tract (such as vomiting) or irritation and inflammation of the pancreas .

Hypersensitivity reactions to doxycycline (e.g. in the form of swelling in the face, mouth and throat and breathing difficulties) are also possible consequences of therapy. These symptoms are considered signs of an allergic reaction. It can turn into a life-threatening anaphylactic shock , which is why a doctor should be alerted immediately if the symptoms mentioned occur.

Other possible side effects of the antibiotic are photosensitization reactions: the active ingredient makes the skin more sensitive to sunlight and UV radiation in solariums. The consequences can be severe sunburn and severe skin damage.

Make sure you use enough sun protection during therapy with doxycycline!

What should be considered when taking doxycycline?


In the case of hypersensitivity to the active substance or to other ingredients in the drug, a different preparation must be used because of the risk of severe allergic shock. Other contraindications (contraindications) are:

  • severe liver dysfunction
  • Simultaneous intake of isotretinoin (active substance for acne therapy)


Experts recommend avoiding alcohol during treatment with doxycycline. In combination with alcohol, the antibiotic is broken down more quickly in the liver , which means that the amount of active substance in the body is too small to achieve the desired therapeutic effect.

Some other drugs such as rifampicin (antibiotic), phenytoin and carbamazepine (antiepileptics) and colestyramine (means for high cholesterol ) weaken the effect of doxycycline.

Doxycycline increases the side effects of coumarins (anticoagulants), sulfonylureas (antidiabetics) and ciclosporin (immunosuppressive agent). In addition, the safety of oral contraceptives can be limited by the antibiotic.

Doxycycline forms poorly soluble complex compounds with calcium and magnesium ions, which impede the absorption of the active substance in the intestine . Dairy products (such as cheese, yoghurt, quark) should therefore not be consumed two hours before and after taking doxycycline.

Therapy with doxycycline can temporarily impair vision and the ability to react. This can make driving or operating machines dangerous.

Sunbathing and visits to the solarium should be avoided during the entire treatment period because the antibiotic makes the skin more sensitive to light.

age restriction

Doxycycline should only be used in children under the age of eight for life-threatening infections. In this age group, the active ingredient can lead to tooth discoloration, tooth enamel defects and bone growth disorders.

pregnancy and breast feeding period

During pregnancy, doxycycline should only be taken if the course of the disease is particularly severe. From the 16th week of pregnancy it is contraindicated (i.e. it must not be given).

In fetuses from four months of age, ingestion of doxycycline often results in stunted bone growth or permanent discoloration of the teeth and enamel defects before the end of the tooth eruption phase.

For the same reasons, women who are breastfeeding and children up to the age of eight are only treated with this active substance to a limited extent. Other antibiotics such as penicillins, cephalosporins and macrolides are preferable.

How to get medication with doxycycline

Doxycycline requires a prescription in Germany, Austria and Switzerland and is only available in pharmacies in any dosage if prescribed by a doctor.

The doxycycline gel available in Germany and Austria for periodontal use (for periodontitis ) is not approved in Switzerland.

Since when is doxycycline known?

The first representative of the tetracyclines, which also includes doxycycline, was discovered in 1948. It was a metabolite of certain bacteria and was called aureomycin.

A little later, another natural tetracycline was discovered in bacteria, oxytetracycline. By modifying its molecular structure in the laboratory, researchers finally arrived at doxycycline. It is one of the best known and most widely used tetracycline antibiotics today.

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