Tetracycline (Class)

Tetracycline is an antibiotic drug used in the treatment of infections that are caused by bacteria.

Overview

Tetracycline is used to treat a great many bacterial infections affecting the skin, lymph nodes, intestines, genitals, respiratory tract, urinary tract, and many other areas of the body. It is regularly used to treat severe acne, and sexually transmitted diseases, such as chlamydia, gonorrhoea, and syphilis. Tetracycline also has its uses addressing the kind of infections you can pick up from having direct contact with contaminated food or infected animals.

It is also useful, under certain circumstances, in treating a number of serious infections (including actinomyces, anthrax, clostridium, and listeria), where the traditional treatment of penicillin is inappropriate.

Tetracyclines are so-named because of their four hydrocarbon rings derivation, and are defined as a subclass of polyketides. They treat the infection by attacking and destroying the bacteria.

Tetracycline works by attacking the bacteria that has caused the infection in question.

There are a number of subsets of tetracycline, including demeclocycline, doxycycline, and minocycline, which are used to treat several other conditions.

Tetracycline will not help to combat viral infections, such as colds and flu, and are only available with a prescription from your doctor, or other healthcare professional.

Tetracycline is a versatile drug, and is available in a number of forms to ease ingestion for the patient. These include syrup, extended-release tablets and capsules, delayed release tablets and capsules, regular tablets and capsules, suspension, and powder for suspension.

Conditions Treated

  • acne – severe
  • actinomyces
  • anthrax
  • borreliosis
  • brucellosis
  • bubonic plague
  • chlamydia
  • clostridium
  • elephantitis filariasis
  • genital infections
  • gonorrea
  • intestinal infections
  • L. venereum infection
  • Legionnaires' disease
  • listeria
  • Lyme disease
  • lymph node infections
  • malaria
  • prophylaxis
  • psittacosis
  • respiratory tract infections
  • rickettsia
  • Rocky Mountain spotted fever
  • rosacea
  • salpingitis
  • skin infections
  • spirochetal infections
  • syphilis
  • trachoma
  • tularemia
  • typhus
  • urethritis
  • urinary tract infections

Type of Medicine

  • Antibiotic

Side Effects

Tetracyclines, in common with most medication, may induce some unwanted side effects along with the desired impact of the treatment. Here we have listed the most commonly reported side effects from this range of drugs, though it should be stated that, given the broad variety of tetracyclines available, this list is not exhaustive. Should any of these conditions occur after you begin your course of treatment, you may need to seek medical attention.

Be sure to check with your doctor immediately if any of these following side effects should occur:

For all tetracyclines

  • increased sensitivity of the skin to sunlight
  • abdominal pain
  • bulging fontanel in infants (the fontanel being the soft spot on the top of the head)
  • headache
  • loss of appetite
  • nausea and vomiting
  • visual changes
  • yellowing skin

For demeclocycline only

  • greatly increased amount of urine, or frequency of urination
  • increased thirst
  • unusual weakness or tiredness

For minocycline only

  • change in pigmentation of mucous membrane and skin (being either a darker color or discoloration)

The following side effects do not usually require the attention of a medical professional. They may go away during your course of treatment as you find your body adjusting to the medication, or your prescribing doctor might be able to offer advice on preventing or minimizing some of the reported side effects. If any of the following conditions continue, or become bothersome to you during your course of treatment, speak with your healthcare professional:

For all tetracyclines

  • burning of the stomach, or cramps
  • diarrhea
  • itching of the genital or rectal areas
  • sore tongue or mouth

For minocycline only

  • unsteadiness, dizziness, or light-headedness

Tetracyclines have been known to cause a darkening or discoloration of the tongue in some patients. Though alarming, this is only a temporary effect, and will go away once you stop taking the medication.

These lists are not exhaustive, and it is possible that other side effects might occur that are not included here. If you notice any side effects that concern you during your course of treatment, be sure to check with your prescribing doctor.

Dosage

The correct dosage of medicines in the tetracycline class will vary from patient to patient, and it is important to always follow the orders of your prescribing doctor, or the instructions on the label. The dosage information that follows merely describes the average doses prescribed for medicines. If your dosage is different, be sure not to change it, unless advised to do so by your doctor or other healthcare professional.

The amount of medicine you will be expected to take will depend on the strength of the medication itself. Likewise, the length of your course of treatment, the frequency of doses, and the time you need to elapse between them, will all depend upon the specific medical condition for which you have been prescribed tetracycline.

For demeclocycline in oral form (tablets)

Adults and teenagers are to take 300 milligrams (mg) every twelve hours, or 150 mg every six hours, for protozoal or bacterial infections.

Adults and teenagers are to take 600mg of demeclocycline on the first day, following up with 300 mg every twelve hours over four days, for treating gonorrhea.

In children over the age of eight, dosage is based on body weight. A usual dose of demeclocycline is 3.3 mg to 6.6 mg per kilogram (kg) (or 1.5 mg to 3 mg per pound) of child's body weight every twelve hours; or 1.65 mg to 3.3 mg per kg (or 0.8 mg to 1.5 mg per pound) of child's body weight every six hours.

Tetracyclines are not used for the treatment of infants and children under the age of eight, as this medication has been known to permanently stain teeth.

For doxycycline in oral forms (capsules, tablets, and suspension)

Adults and children over 45 kilograms (kg) (or 99 pounds) are to take 100 milligrams (mg) every 12 hours for the first day, and then 100 mg per day, or 50 mg to 100 mg every twelve hours.

In children over the age of eight, who weigh less than 45 kg (or 99 pounds), dosage is based on body weight. A usual dose of doxycycline is 2.2 mg per kg (or 1 mg per pound) of child's body weight twice a day for the first day, then 2.2 mg to 4.4 mg per kg (or 1 mg to 2 mg per pound) of child's body weight once a day, or 1.1 mg to 2.2 mg per kg (0.5 mg to 1 mg per pound) of child's body weight two times a day.

For doxycycline taken for the prevention of malaria

Adults and teenagers are to take 100 milligrams (mg) once a day. The first dose should be taken 1 or 2 days prior to travelling to a malaria-risk area, the medicine should continue to be taken every day during travel, and for an additional four weeks following your return from the malarial area.

In children over the age of eight, dosage is based on body weight. A usual dose of doxycycline is 2 mg per kilogram (kg) (or, 0.9 mg per pound) of child's body weight every day. The first dose should be taken 1 or 2 days prior to travelling to a malaria-risk area. The medicine should continue to be taken every day during travel, and for an additional four weeks following your return from the malarial area.

For doxycycline in injection form

Adults and children over 45 kilograms (or 99 pounds) are to take 200 milligrams (mg), injected slowly into a vein once every day, or 100 mg injected slowly into their vein every twelve hours on the first day, then 100 mg to 200 mg injected slowly into their vein once per day, or 50 mg to 100 mg injected slowly into the vein every twelve hours.

In children over the age of eight, who weigh less than 45 kg (or 99 pounds), dosage is based on body weight. A usual dose of doxycycline is 4.4 mg per kg (or 2 mg per pound) of child's body weight every day, injected slowly into a vein, or 2.2 mg per kg (or 1 mg per pound) of child's body weight injected slowly into the vein every twelve hours on the first day, then 2.2 mg to 4.4 mg per kg (1 mg to 2 mg per pound) of the child's body weight once a day, or 1.1 mg to 2.2 mg per kg (0.5 mg to 1 mg per pound) of the child's body weight every 12 hours.

For minocycline in oral form (capsules and suspension)

Adults and teenagers are to take 200 milligrams (mg) to start with, then 100 mg every 12 hours, or 100 mg to 200 mg to start with, then 50 mg every six hours, for protozoal or bacterial infections.

In children over the age of eight, dosage is based on body weight. A usual dose of minocycline is 4 mg per kilogram (kg) (or 1.8 mg per pound) of child's body weight at first, then 2 mg per kg (or 0.9 mg per pound) of child's body weight every twelve hours.

For minocycline in injection form

Adults and teenagers are to take 200 milligrams (mg) at first, then 100 mg every 12 hours, to be injected slowly into a vein.

In children over the age of eight, dosage is based on body weight. A usual dose of minocycline is 4 mg per kilogram (kg) (or 1.8 mg per pound) of child's body weight at first, then 2 mg per kg (or 0.9 mg per pound) of child's body weight every twelve hours, to be injected slowly into a vein.

For oxytetracycline in oral form (capsules)

Adults and teenagers are to take 250 milligrams (mg) to 500 mg every six hours, for protozoal or bacterial infections.

In children over the age of eight, dosage is based on body weight. A usual dose of oxytetracycline is 6.25 mg to 12.5 mg per kg (or 2.8 mg to 5.7 mg per pound) of child's body weight every six hours.

For oxytetracycline in injection form

Adults and teenagers are to take 100 milligrams (mg) every 8 hours, 150 mg every 12 hours, or 250 mg per day, to be injected into a muscle.

In children over the age of eight, dosage is based on body weight. A usual dose of oxytetracycline is 5 mg to 8.3 mg per kilogram (kg) (or 2.3 mg to 3.8 mg per pound) of child's body weight every eight hours, or 7.5 mg to 12.5 mg per kg (or 3.4 mg to 5.7 mg per pound) of child's body weight every twelve hours, to be injected into a muscle.

For tetracycline in oral form (capsules and suspension)

Adults and teenagers are to take 500 milligrams (mg) to 1 gram (g) every twelve hours; or 250 mg to 500 mg every six hours, for protozoal or bacterial infections.

Adults and teenagers are to take 1.5 g of tetracycline as a first dose, following up with 500 mg every six hours over four days, for treating gonorrhea.

In children over the age of eight, dosage is based on body weight. A usual dose of tetracycline is 12.5 mg to 25 mg per kilogram (kg) (or 5.7 mg to 11.4 mg per pound) of child's body weight every twelve hours; or 6.25 mg to 12.5 mg per kg (or 2.8 mg to 5.7 mg per pound) of child's body weight every six hours.

If you miss a given dose during your course of medication, you should try to take it as soon as possible. If it is nearly time for your next dosage, you should skip the dose you missed, and return to your regular dosage schedule. Under no circumstances should you double doses.

You should take tetracycline with a full glass of water, as this prevents irritation of the esophagus or stomach. Additionally, most tetracyclines (aside from doxycycline and minocycline) work best if taken on an empty stomach. It is recommended to take your medicine within an hour before or two hours after meals. Should you react to the medicine with an upset stomach, your prescribing doctor may wish you to take your dosage with food.

Apart from doxycycline and minocycline, you should not consume milk, milk formula, or any other dairy product within one to two hours of when you are taking tetracyclines by mouth, as they may prevent this medication from working properly.

If your medication changes color, looks or tastes different, has become outdated, or stored incorrectly (usually a too damp, or too warm environment), do not take it, as it may cause severe side effects. Be sure to throw any of the remaining medicine away. Your healthcare professional will be able to advise you on the best way to do this.

If prescribed the oral liquid form of tetracycline, you should use a specially marked measuring spoon, or similar device to measure each required dose accurately. A regular household teaspoon might not hold the correct amount of liquid.

If taking doxycycline or minocycline, you are allowed to take these drugs with milk or food, should they upset your stomach.

Be sure to swallow the capsule form of doxycycline whole. In no event should you crush or break it.

Even if you begin to feel better within a few days, in order to clear your infection entirely, you should continue taking the tetracycline for the full course of treatment as recommended by your doctor. If you stop your treatment too early, you run the risk of your symptoms returning.

Tetracycline works best if it maintains a constant level in the urine or blood. In order to keep the level constant, ensure you do not miss any of your prescribed doses. Likewise, it is advised that you take your dosage at evenly spaced times throughout the day and night. For instance, should you be prescribed four doses per day, these should be spaced about six hours apart. Should this interfere with your daily activities, or your regular sleep pattern, or should you need assistance in planning the best time to take your medication, please check with your prescribing doctor.

Major Drug Interactions

Although some medications ought not to be used in conjunction with one another, in certain circumstances two different drugs might have to be utilised at the same time, even though an interaction may occur. In such cases, your prescribing doctor might want to alter the dosage, or advise alternative precautions. When taking any tetracycline-based medication, it is of vital importance that you make your doctor aware whether you are also currently prescribed any of the following drugs listed here. These interactions are included here due to their possible significance, though the list itself is not necessarily exhaustive.

Using tetracyclines with the following drugs is not to be advised. Your prescribing doctor might choose not to administer this type of medication, or may decide to alter one or more of your currently prescribed drugs.

  • acitretin
  • methoxyflurane

Using tetracyclines with the medicines on this next list is normally not advisable, but it may be a requirement in certain circumstances. If both medications are prescribed at the same time, your prescribing doctor may choose to change your dosage, or the frequency with which you take either of the medications.

  • amoxicillin
  • tretinoin
  • ampicillin
  • temocillin
  • atazanavir
  • sultamicillin
  • bacampicillin
  • pivampicillin
  • bexarotene
  • piperacillin
  • cholera vaccine, live
  • penicillin V
  • cloxacillin
  • penicillin G procaine
  • dicloxacillin
  • penicillin G benzathine
  • digoxin
  • penicillin G
  • etretinate
  • oxacillin
  • isotretinoin
  • nafcillin
  • methicillin
  • methoxyflurane
  • methotrexate

The presence of certain medical conditions may impact the use of tetracyclines. If you have any medical problems, be sure to inform your doctor, especially if it is one of the following:

  • diabetes insipidus (water diabetes)
  • kidney disease (note: this does not apply to patients being treated with minocycline or doxycycline)
  • liver disease

Warnings

Inform your prescribing doctor about previously exhibiting any allergic or unusual reaction to tetracyclines, or any other medication. Also be sure to inform your prescribing whether you have ever had any other kind of allergies, including allergies to animals, dyes, preservatives, or foods.

Many tetracyclines have been known to cause a permanent discoloration of teeth, as well as slowing down bone growth. As such, none of these medications should be given to any child aged eight years and under, unless the child's doctor directs otherwise.

Use of tetracyclines is not advisable throughout the latter half of a patient's pregnancy. If taken during that time, there are indications that they might cause the teeth of the unborn infant to become discolored, as well as possibly slowing down the growth of the baby's bones and teeth. Additionally, liver problems have been reported to occur in some pregnant women, particularly those taking high doses of the drug through an injection into a vein.

Use of tetracyclines is not to be advised whilst the patient is breastfeeding, as the drug is known to pass into breast milk. This might cause the teeth of the nursing baby to become discolored and, as advised regarding its use during pregnancy, might slow down the growth of the infant's bones. Tetratcyclines might also raise the sensitivity of the child's skin to sunlight, or cause a fungal infection of the infant's mouth and vagina. Additionally, use of minocycline has been known to cause unsteadiness, dizziness, or light-headedness in nursing babies.

If your symptoms have not improved within the course of a few days (or possibly a few weeks or months, if you're taking the drug for acne), or should they worsen, make an appointment to see your doctor.

Oral contraceptives (birth control pills) that contain estrogen might not work properly when taken alongside tetracyclines, and unplanned pregnancies might occur. During the course of your treatment, you should use additional, or different, means of contraception. If you have any concerns in this area, you should speak to your prescribing doctor.

Should you be due to have any kind of surgery (including dental surgery) that requires a general anesthetic, be sure to tell the dentist or medical doctor in charge that you are currently on a course of tetracycline. This need not apply to doxycycline.

Tetracyclines are known to make your skin increasingly sensitive under direct sunlight, more so than usual. Exposure to direct sunlight, if only for a brief period, may cause itching, redness, skin rashes, a severe sunburn, or some other kind of skin discoloration. When you start taking this medication you should:

Avoid sunlight where possible, particularly between ten in the morning, and three in the afternoon.

Wear clothing that covers and protects, including sunglasses and a hat.

Apply sun block with an SPF (skin protection factor) of 15 or above. You might require a sun block product that has and even higher skin protection factor, particularly if your complexion is especially fair. Should you need further information regarding this, you should check up with a medical expert.

To keep your lips protected, be sure to apply a sun block lipstick, one with a minimum SPF of 15.

Avoid using tanning beds, tanning booths, and sunlamps during your course of treatment.

You may well remain more sensitive to sunlamps and sunlight for anywhere from two weeks to several months following your course of treatment. Should you react severely, you will need to speak to your doctor.

For patients taking minocycline:

Minocycline has been shown to make some people become unsteady, dizzy, or light-headed. Ensure you are aware of how you react to the medication before trying to drive, use machinery, or engage in any other activity that might be dangerous if not sufficiently alert. Should these reactions become especially bothersome, be sure to check with your prescribing doctor.

Storage

Tetracycline should always be kept away from children.

The medication should be stored at room temperature, in a closed container, and kept away from direct light, moisture, and heat. You must be sure to keep it from freezing, too.

Medicine that is no longer needed, or is outdated, should not be kept. Speak to your prescribing doctor regarding how you should dispose of such unwanted medication.

Summary

Despite concerns over its reduced effectiveness in the wake of antibiotic resistance, the tetracycline group of broad-spectrum antibiotic drugs remains the recommended treatment for a number of skin conditions and bacterial infections. Its wide range of forms of administration make it a popular and versatile choice for doctors to prescribe, as it can be tailored to suit conditions with different levels of severity.

Though there are a number of recognised side effects with the drugs, only a few of them are serious or persistent.

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Last Reviewed:
December 24, 2017
Last Updated:
April 03, 2018
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