Are there any serious risks from receiving Elcys (cysteine)?

Some serious [risks](https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=e7652275-1c53-490c-82ad-e63867df5788&type=display#section-5) from receiving Elcys (cysteine) include [pulmonary embolism](https://www.goodrx.com/conditions/pulmonary-embolism/blood-clot-lung-symptoms) (blood clot in the lungs), kidney or liver problems, [metabolic acidosis](https://medlineplus.gov/ency/article/000335.htm) (too much acid in the body), high ammonia levels, and aluminum toxicity (this medication contains aluminum). Preterm infants (babies born too early) are at a higher risk for aluminum toxicity since their kidneys aren't fully developed, and they often require other solutions that contain aluminum. Your provider will monitor certain labs to make sure you aren't getting any serious side effects from Elcys (cysteine).

Who shouldn't receive Elcys (cysteine)?

You shouldn't receive Elcys (cysteine) if you have a history of an allergic reaction to one or more amino acids, or if you have [problems with breaking down amino acids](https://www.hindawi.com/journals/jnme/2018/5629454/) (e.g., [homocystinuria or HCU](https://rarediseases.info.nih.gov/diseases/10770/homocystinuria), [phenylketonuria or PKU](https://rarediseases.info.nih.gov/diseases/7383/phenylketonuria)). You also shouldn't receive Elcys (cysteine) if you have a buildup of fluid in your lungs or too much acid in your body due to certain heart problems. Discuss your full medical history with your provider to make sure Elcys (cysteine) is safe for you.

Elcys

Q: What is Elcys (cysteine)?

Elcys (cysteine) is an [amino acid](https://medlineplus.gov/ency/article/002222.htm), which is a molecule that forms proteins. It's added to TPN as a supplement for people who can't make enough natural cysteine in their body. Specifically, it's used in newborn infants who require TPN, as well as children and adults with severe liver problems who require TPN.

Q: How is Elcys (cysteine) given?

Elcys (cysteine) is added to parenteral nutrition solutions and then given as an intravenous (IV) infusion by a trained healthcare provider. It should never be directly given into the vein and must be diluted (mixed with another solution) first to avoid vein damage. Your provider will calculate your dose based on your age and nutrition requirements. They'll also make sure you get the correct dose at the right time.

Q: What are the side effects of Elcys (cysteine)?

Some [side effects](https://dailymed.nlm.nih.gov/dailymed/fda/fdaDrugXsl.cfm?setid=e7652275-1c53-490c-82ad-e63867df5788&type=display#section-6) include infusion site reactions (warm sensation, redness, vein inflammation, blood clot), fever, nausea, and flushing (feeling warm all of a sudden). If you experience any side effects while getting Elcys (cysteine), let your provider know.

cysteine

Used for Nutritional Deficiency

Elcys (cysteine) is an injectable supplement added to amino acid solutions for people who require total parenteral nutrition (TPN). TPN is a way to get nutrition when you're unable to eat or drink. This medication is only available as brand name so it might be expensive.

Reviewed by:

Kristianne Hannemann, PharmD

Allison Gourley, PharmD

Last reviewed on July 11, 2022

What is Elcys (cysteine)?

What is Elcys (cysteine) used for?

Cysteine supplement in newborn infants requiring TPN
Cysteine supplement in children and adults with severe liver problems who require TPN

Are you looking for information on acetylcysteine nebulized solution instead?

Drug facts

Common Brands	Elcys
Drug Class	Amino acid
Controlled Substance Classification	Not a controlled medication
Generic Status	No lower-cost generic available
Availability	Prescription only

Common Brands

Elcys

Drug Class

Amino acid

Controlled Substance Classification

Not a controlled medication

Generic Status

No lower-cost generic available

Availability

Prescription only

Common questions about Elcys

Elcys is an amino acid, which is a molecule that forms proteins. It's added to TPN as a supplement for people who can't make enough natural cysteine in their body. Specifically, it's used in newborn infants who require TPN, as well as children and adults with severe liver problems who require TPN.

Elcys is added to parenteral nutrition solutions and then given as an intravenous (IV) infusion by a trained healthcare provider. It should never be directly given into the vein and must be diluted (mixed with another solution) first to avoid vein damage. Your provider will calculate your dose based on your age and nutrition requirements. They'll also make sure you get the correct dose at the right time.

Some side effects include infusion site reactions (warm sensation, redness, vein inflammation, blood clot), fever, nausea, and flushing (feeling warm all of a sudden). If you experience any side effects while getting Elcys, let your provider know.

Some serious risks from receiving Elcys include pulmonary embolism (blood clot in the lungs), kidney or liver problems, metabolic acidosis (too much acid in the body), high ammonia levels, and aluminum toxicity (this medication contains aluminum). Preterm infants (babies born too early) are at a higher risk for aluminum toxicity since their kidneys aren't fully developed, and they often require other solutions that contain aluminum. Your provider will monitor certain labs to make sure you aren't getting any serious side effects from Elcys.

You shouldn't receive Elcys if you have a history of an allergic reaction to one or more amino acids, or if you have problems with breaking down amino acids (e.g., homocystinuria or HCU, phenylketonuria or PKU). You also shouldn't receive Elcys if you have a buildup of fluid in your lungs or too much acid in your body due to certain heart problems. Discuss your full medical history with your provider to make sure Elcys is safe for you.