Lymepak (doxycycline hyclate)

What is Lymepak, and how does it work?

Lymepak is a prescription medicine used for the treatment of early Lyme disease due to a bacteria known as Borrelia burgdorferi in adults and children 8 years of age and older weighing 99 pounds (lbs) (45 kg) and above.

It is not known if Lymepak is safe and effective in children less than 8 years of age or weighing under 99 lbs (45 kg).

What are the side effects of Lymepak?

Lymepak may cause serious side effects, including:

  • Harm to an unborn baby.
  • Harm to infants and children under 8 years of age:
    • Permanent teeth discoloration. Lymepak may permanently turn a baby or child's teeth yellow-gray-brown during tooth development.
    • Slow bone growth. Lymepak may slow bone growth in infants and children. Slow bone growth is reversible after stopping treatment with Lymepak.
  • Diarrhea. Diarrhea can happen with most antibiotics, including Lymepak. This diarrhea may be caused by an infection (Clostridium Difficile) in your intestines. Call your doctor right away if you get watery or bloody stools, this can happen anytime while on Lymepak, or even two or more months after taking your last dose.
  • Severe Skin Reactions Stop taking Lymepak and tell your doctor right away if you get any of the following symptoms during treatment with Lymepak:
  • Jarisch-Herxheimer Reaction. This reaction can happen in people with early Lyme Disease and begins one to two hours after the first dose of Lymepak and disappears within 12 to 24 hours. The reaction may include fever, chills, muscle pain, headache, worsening of skin lesions, fast heart rate, fast breathing, flushing of skin, and increase in blood pressure. Tell your doctor if you have any of these symptoms.
  • Increased pressure around the brain (intracranial hypertension). This condition may lead to vision changes and permanent vision loss. You may be more likely to get intracranial hypertension if you are female of childbearing age and are overweight or have a history of intracranial hypertension. Stop taking Lymepak and call your doctor right away if you have blurred or double vision, vision loss, or unusual headaches.

If you have any of the above serious side effects during treatment with Lymepak, your doctor may stop your treatment.

Common side effects of Lymepak include:

These are not all the possible side effects of Lymepak.

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088. You may also report side effects to Chartwell RX, LLC at 1-845-232-1683.

What is the dosage for Lymepak?


Adults And Pediatric Patients 8 Years Of Age And Older Weighing 45 kg And Above

Administer Lymepak (100 mg) tablet every 12 hours for 21 days.

Important Administration Instructions

  • The usual dosage and frequency of administration of Lymepak differs from that of the other tetracyclines. Exceeding the recommended dosage may result in an increased incidence of adverse reactions.
  • Administration of adequate amounts of fluid along with the tablets is recommended to wash down the tablet to reduce the risk of esophageal irritation and ulceration.
  • If gastric irritation occurs, Lymepak may be given with food or milk. The absorption of doxycycline is not markedly influenced by simultaneous ingestion of food or milk.

What drugs interact with Lymepak?

Anticoagulant Drugs

  • Because tetracyclines have been shown to depress plasma prothrombin activity, patients who are on anticoagulant therapy may require downward adjustment of their anticoagulant dosage.


  • Since bacteriostatic drugs may interfere with the bactericidal action of penicillin, it is advisable to avoid giving tetracyclines, including Lymepak in conjunction with penicillin.

Antacids And Iron Preparations

  • Absorption of tetracyclines is impaired by antacids containing aluminum, calcium, or magnesium, bismuth subsalicylate, and iron-containing preparations.
  • Absorption of tetracyclines is impaired by bismuth subsalicylate.

Oral Contraceptives


Barbiturates And Anti-Epileptics

Drug/Laboratory Test Interactions

  • False elevations of urinary catecholamines may occur due to interference with the fluorescence test.


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Is Lymepak safe to use while pregnant or breastfeeding?

  • Lymepak, like other tetracycline-class antibacterial drugs, may cause discoloration of deciduous teeth and reversible inhibition of bone growth when administered during the second and third trimester of pregnancy.
  • Available data from published studies over decades have not shown a difference in major birth defect risk compared to unexposed pregnancies with doxycycline exposure in the first trimester of pregnancy.
  • There are no available data on the risk of miscarriage following exposure to doxycycline in pregnancy.
  • Based on available published data, doxycycline is present in human milk.
  • There are no data that inform the levels of doxycycline in breastmilk, the effects on the breastfed infant, or the effects on milk production.
  • Because there are other antibacterial drug options available to treat Lyme disease in lactating women and because of the potential for serious adverse reactions, including tooth discoloration and inhibition of bone growth, advise patients that breastfeeding is not recommended during treatment with Lymepak and for 5 days after the last dose.


Lymepak is a prescription medicine used for the treatment of early Lyme disease due to a bacteria known as Borrelia burgdorferi in adults and children 8 years of age and older weighing 99 pounds (lbs) (45 kg) and above. Serious side effects of Lymepak include harm to an unborn baby, harm to infants and children under 8 years of age, diarrhea, severe skin reactions, Jarisch-Herxheimer reaction, and increased pressure around the brain.

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You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

All sections courtesy of the U.S. Food and Drug Administration