Generic Name: cysteine (SIS-te-een)
Medically reviewed by Drugs.com. Last updated on Jan 1, 2021.
Commonly used brand name(s)
In the U.S.
Available Dosage Forms:
Therapeutic Class: Amino Acid Supplement
Uses for cysteine
Cysteine injection is used to meet the nutritional requirements of newborn infants (including preterm babies) requiring total parenteral nutrition (TPN).
Cysteine injection is also given to adults and children with severe liver disease who may have impaired enzymatic processes and require TPN. Cysteine may be also used to provide a more complete profile of amino acids for protein synthesis.
Cysteine is to be given only by or under the direct supervision of your doctor.
Before using cysteine
In deciding to use a medicine, the risks of taking the medicine must be weighed against the good it will do. This is a decision you and your doctor will make. For cysteine, the following should be considered:
Tell your doctor if you have ever had any unusual or allergic reaction to cysteine or any other medicines. Also tell your health care professional if you have any other types of allergies, such as to foods, dyes, preservatives, or animals. For non-prescription products, read the label or package ingredients carefully.
Appropriate studies performed to date have not demonstrated pediatric-specific problems that would limit the usefulness of cysteine injection in children. However, children are more likely to have immature kidney and liver functions, which may require caution in patients receiving cysteine.
Appropriate studies on the relationship of age to the effects of cysteine injection have not been performed in the geriatric population. Safety and efficacy have not been established.
There are no adequate studies in women for determining infant risk when using this medication during breastfeeding. Weigh the potential benefits against the potential risks before taking this medication while breastfeeding.
Interactions with medicines
Although certain medicines should not be used together at all, in other cases two different medicines may be used together even if an interaction might occur. In these cases, your doctor may want to change the dose, or other precautions may be necessary. Tell your healthcare professional if you are taking any other prescription or nonprescription (over-the-counter [OTC]) medicine.
Interactions with food/tobacco/alcohol
Certain medicines should not be used at or around the time of eating food or eating certain types of food since interactions may occur. Using alcohol or tobacco with certain medicines may also cause interactions to occur. Discuss with your healthcare professional the use of your medicine with food, alcohol, or tobacco.
Other medical problems
The presence of other medical problems may affect the use of cysteine. Make sure you tell your doctor if you have any other medical problems, especially:
- Acid-base imbalance or
- Electrolyte imbalance—Should be corrected first before receiving cysteine.
- Acidosis (caused by low cardiac output) or
- Amino acid metabolism, inborn error or
- Pulmonary edema (fluid in the lungs)—Should not be used in patients with these conditions.
- Gallstones or
- Hyperammonemia (high ammonia levels in the blood) or
- Liver disease—Use with caution. May make these conditions worse.
- Kidney disease—Giving cysteine for a long time in preterm babies may increase risk for aluminum toxicity.
Proper use of cysteine
A nurse or other trained health professional will give you or your child cysteine. Cysteine is added to your or your baby's TPN bag. After mixing, it is given through a needle placed in one of your or your baby's veins.
Precautions while using cysteine
Your doctor will check your or your child's progress closely while you are receiving cysteine. This will allow your doctor to see if the medicine is working properly. Blood and urine tests will be needed to check for unwanted effects.
Tell your doctor right away if you or your child have chest pain, cough, fainting, fast heartbeat, trouble breathing, or dizziness or lightheadedness after receiving cysteine. These could be symptoms of pulmonary embolism caused by the precipitates found in the TPN solution, infusion set, and catheter.
Tell your doctor if you or your child develop pain, tenderness, changes in skin color, or swelling of foot or leg after receiving cysteine. These could be symptoms of a vein damage or thrombophlebitis.
Check with your doctor right away if you have pain or tenderness in the upper stomach, pale stools, dark urine, loss of appetite, nausea, vomiting, or yellow eyes or skin. These could be symptoms of a serious liver problem.
Cysteine side effects
Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.
Check with your doctor or nurse immediately if any of the following side effects occur:
Incidence not known
- chest pain
- confusion cough
- dizziness or lightheadedness
- fast heartbeat
- feeling of warmth
- muscle tremors
- pain, tenderness, or swelling of the foot or leg
- rapid, deep breathing
- redness of the face, neck, arms, and occasionally, upper chest
- stomach cramps
- sudden shortness of breath or troubled breathing
- unusual tiredness or weakness
- warmth, redness, pain, or changes in skin color at the infusion site
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
Call your doctor for medical advice about side effects. You may report side effects to the FDA at 1-800-FDA-1088.
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Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.