Generic Name: lysine (LYE seen)
Brand Name: L-Formula
Medically reviewed on August 3, 2018
What is lysine?
Lysine is an amino acid (building block of protein), and it is also known as L-2,6-diaminohexanoic acid, Lisina, Lys, Lysine Hydrochloride, Lysine Monohydrochloride, and other names.
Lysine has been used in alternative medicine as a possibly effective aid in treating cold sores due to herpes simplex.
It is not certain whether lysine is effective in treating any medical condition. Medicinal use of this product has not been approved by the FDA. Lysine should not be used in place of medication prescribed for you by your doctor.
Lysine is often sold as an herbal supplement. There are no regulated manufacturing standards in place for many herbal compounds and some marketed supplements have been found to be contaminated with toxic metals or other drugs. Herbal/health supplements should be purchased from a reliable source to minimize the risk of contamination.
Lysine may also be used for purposes not listed in this product guide.
Follow all directions on the product label and package. Tell each of your healthcare providers about all your medical conditions, allergies, and all medicines you use.
Before taking this medicine
Before using lysine, talk to your healthcare provider. You may not be able to use lysine if you have certain medical conditions.
Ask a doctor, pharmacist, or other healthcare provider if it is safe for you to use this product if you have:
lysinuric protein intolerance (in children); or
It is not known whether lysine will harm an unborn baby. Do not use this product without medical advice if you are pregnant.
It is not known whether lysine passes into breast milk or if it could harm a nursing baby. Do not use this product without medical advice if you are breast-feeding a baby.
Do not give any herbal/health supplement to a child without medical advice.
How should I take lysine?
When considering the use of herbal supplements, seek the advice of your doctor. You may also consider consulting a practitioner who is trained in the use of herbal/health supplements.
If you choose to use lysine, use it as directed on the package or as directed by your doctor, pharmacist, or other healthcare provider. Do not use more of this product than is recommended on the label.
Do not use different formulations of lysine (such as tablets, liquids, and others) at the same time, unless specifically directed to do so by a health care professional. Using different formulations together increases the risk of an overdose.
Call your doctor if the condition you are treating with lysine does not improve, or if it gets worse while using this product.
Store at room temperature away from moisture and heat.
What happens if I miss a dose?
Skip the missed dose if it is almost time for your next scheduled dose. Do not use extra lysine to make up the missed dose.
What happens if I overdose?
Seek emergency medical attention or call the Poison Help line at 1-800-222-1222.
What should I avoid while taking lysine?
Follow your healthcare provider's instructions about any restrictions on food, beverages, or activity.
Lysine can increase how much calcium your body absorbs. Avoid taking large amounts of calcium when taking lysine.
Lysine side effects
Get emergency medical help if you have signs of an allergic reaction: hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
Although not all side effects are known, lysine is thought to be possibly safe when taken for up to a year.
Common side effects may include:
stomach pain and diarrhea.
This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.
See also: Side effects (in more detail)
What other drugs will affect lysine?
Other drugs may interact with lysine, including prescription and over-the-counter medicines, vitamins, and herbal products. Tell each of your health care providers about all medicines you use now and any medicine you start or stop using.
Do not take lysine without medical advice if you are using any of the following medications:
calcium supplements; or
gastrointestinal medicines (such as prucalopride or tegaserod).
This list is not complete. Other drugs may interact with lysine, including prescription and over-the-counter medicines, vitamins, and herbal products. Not all possible interactions are listed in this product guide.
- Consult with a licensed healthcare professional before using any herbal/health supplement. Whether you are treated by a medical doctor or a practitioner trained in the use of natural medicines/supplements, make sure all your healthcare providers know about all of your medical conditions and treatments.
Remember, keep this and all other medicines out of the reach of children, never share your medicines with others, and use this medication only for the indication prescribed.
Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.
Copyright 1996-2018 Cerner Multum, Inc. Version: 4.01.