L-Lysine Side Effects, Dangers, Drug Interactions & Contraindications

L-Lysine side effects are generally mild and this supplement is well tolerated in the majority of users. However, this essential amino acid can cause adverse reactions in some individuals, including gastrointestinal side effects.

L-lysine supplements may be used for a variety of purposes, ranging from body building to the treatment of cold sores caused by herpes simplex labialis. Some people also take these supplements in order to resolve L-lysine deficiencies, as this amino acid is essential for the proper functioning of the human body.

Although L-lysine supplements are rated Possibly Safe when used appropriately, they may still cause side effects for some consumers. In order to minimize the risk of L-lysine side effects, consumers are encouraged to use caution when taking supplements for any purpose.

Consumers should also consult a physician before taking this supplement to make sure that it is a safe and appropriate choice for you.

Lysine

Amino Acid

Immunity

Skin

Longevity

How It Works:

• Promotes health skin & bones
• Boosts immunity & antibody production
• Supports tissue repair & hormone balance

Dosage:

Between 1 - 3 g per day

Safety:

Rated Possibly Safe

Top Lysine Products* ❯

View User Ratings* ❯

What is L-Lysine?

L-lysine is one of 20 amino acids the body requires for protein synthesis.

Because the body cannot make L-lysine on its own, this essential amino acid must be obtained entirely from dietary sources, such as eggs, dairy and fish.

Not having enough L-lysine may cause symptoms, including infertility, anemia, irritability and impaired immune function. For this reason, some people choose to take L-lysine supplements if they believe their dietary sources to be insufficient.

According to the Natural Medicines Database, people also take L-lysine supplements to increase muscle mass, to improve the condition of hair and skin and for certain illnesses.

It is believed to stimulate the release of growth hormone (GH), help fight the symptoms of the herpes simplex virus, improve heart health and prevents nitric oxide over-production.

It is commonly used in conjunction with other amino acids, including L-Arginine and L-Proline, as well as Vitamin C.

Is L-Lysine Safe?

L-lysine supplements are rated as Possibly Safe when used appropriately and for no more than one year at a time.

However, some people may still experience side effects, especially if high dosages are consumed. Some of the immediate side effects of too much lysine may include:

• Abdominal cramps
• Nausea
• Heartburn
• Diarrhea
• Dyspepsia (Indigestion)

Over time, other long-term side effects may develop from Lysine supplementation, including:

• Problems with renal function
• Gallstones
• Elevated cholesterol levels

Some case reports have also suggested a connection between L-lysine and severe tubulointerstitial nephritis, chronic renal failure and the development of Fanconi’s syndrome.

It is not yet known whether L-lysine was the cause of the condition in these cases. Further research is required.

L-Lysine and Hair Loss

L-lysine is often used to treat hair loss or to strengthen hair. In fact, studies have supported L-lysine’s ability to improve symptoms among women with increased hair shedding.

However, some people taking high dosages of this supplement have reported hair loss as a side effect.

L-Lysine and Weight Gain

Some studies have indicated that consuming L-lysine as a supplement could contribute to weight gain, especially with physical activity.

Specifically, in a study involving horses, researchers found that horses who exercised after receiving a lysine supplement were more likely to gain weight in the form of muscle mass than horses that did not receive the supplement.

It is this purported property of L-lysine that makes the supplement appealing to bodybuilders.

Lysinuric protein intolerance

Lysinuric protein intolerance (LPI) is a rare condition that affects approximately 1 out of 60,000 people. Individuals with LPI are unable to break down proteins into their constituent amino acids upon digestion.

LPI can cause a number of serious health problems, including short stature, muscle weakness, enlarged liver and spleen as well as increase the risk of bone fratures.

Individuals with LPI are recommended to avoid supplements and foods that contain lysine, arginine, and ornithine. Consumption of these foods can result in nausea and vomiting because the body is unable to properly digest them.

Safe L-Lysine Dosages

In order to reduce the risk of negative side effects while taking L-lysine supplements, consumers should never take more than the recommended dosage.

Because this dietary supplement has not been approved for the treatment of any disorder or condition, standardized dosing guidelines are not currently available.

However, a range of dosages have been used in clinical trials without significant adverse effects. Some of these dosages include:

• Growth promotion in childhood – 0.66 g of lysine in three divided doses daily for up to six months.
• Aphthous ulcers – 1,000 mg daily for treatment and 500 mg daily for prevention.
• Ocular disorders – 6 g bolus of lysine on day one followed by 2 g of oral lysine five times daily for one week.
• Herpes infections – Up to 3,000 mg of lysine daily for up to one year.

Keep in mind that every person requires a certain amount of this amino acid on a daily basis in order to synthesize protein properly.

Currently, the recommended dietary allowance of lysine for adults is 38 mg per kg of body weight.

There are a number of different forms of this compound that have been studied in double-blind placebo-controlled clinical trials. Depending on the form taken, the dosage may need to be adjusted. Some forms of this product include:

• L-Lysine Hydrochloride (HCL)
• Lysine Acetylsalicylate
• Lysine Clonixinate
• L-Lysine Monohydrochloride

L-Lysine Interactions and Contraindications

L-lysine may interact with certain medications and other dietary supplements, including 5-HT4 agonists and calcium. Talk to your doctor before taking this amino acid if you are using either of these substances.

Consult with a doctor before using Lysine and Vitamin C with cholesterol-lowering drugs as this combination may interfere with the effects of these drugs.

L-lysine supplementation may also be unsafe for people with certain pre-existing conditions, including:

• Lysinuric Protein Intolerance – Individuals with lysinuric protein intolerance may experience severe stomach cramps and diarrhea while taking L-lysine supplements.
• Osteoporosis – L-lysine may affect how calcium is absorbed and excreted.
• Kidney Disease – Because of case reports linking L-lysine supplements to kidney problems, people with pre-existing kidney problems should consider the potential risks of L-lysine supplements carefully. Supplementation can increase calcium absorption.

As with any supplement, you should always talk to a licensed physician before adding L-lysine to your regimen.

Never take more of this supplement than you need to achieve the desired effect, and never exceed the dosage recommended by your doctor.

If you experience L-lysine side effects that are severe or bothersome, discontinue your use of the supplement and consult your physician.

Rate This Article

(27 votes, average: 3.85 out of 5, rated)