Reviewed on 4/22/2022

What Is Caffeine and How Does It Work?

Caffeine is a prescription and over-the-counter (OTC) medication used to treat the symptoms of fatigue, drowsiness, and respiratory failure.  

  • Caffeine is available under the following different brand names: Cafcit, NoDoz, ReCharge, Vivarin

What Are Dosages of Caffeine?

Adult and pediatric dosage

Injectable solution

  • 10mg/mL
  • 20mg/mL

Oral solution

  • 10mg/mL
  • 20mg/mL


  • 200mg


  • 200mg


  • 75mg

Fatigue & Drowsiness

Adult dosage

  • 100-200 mg orally every 3-4 hours; not later than 6 hours before bedtime

Pediatric dosage

  • Children below 12 years: Not recommended
  • Children above 12 years: 100-200 mg orally every 3-4 hours; not later than 6 hours before bedtime
  • The potential toxic dose for children 6 years old: 15 mg/kg

Respiratory Failure

Adult dosage

  • Caffeine and sodium benzoate: 250 mg IV/IM once; may repeat as needed; alternatively, 500 mg in 1 L IV over 4 hours; not to exceed 2500 mg/24hour

Neonatal Apnea

Pediatric dosage

  • Load: 10-20 mg/kg IV/orally once  
  • Maintenance: 5-10 mg/kg IV/orally once daily
  • The potential toxic dose for children less than 6 years old: 15 mg/kg

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”


Sleep Disorders: Foods That Help Sleep or Keep You Awake See Slideshow

What Are Side Effects Associated with Using Caffeine?

Common side effects of Caffeine include:

  • fussiness,
  • excessive crying,
  • skin rash,
  • irritable or restless behavior,
  • nausea, 
  • vomiting, 
  • stomach upset, 
  • headache, 
  • trouble sleeping, 
  • restlessness, 
  • poor feeding, 
  • increased urination, and
  • dry skin.

Serious side effects of Caffeine include:

  • hives,
  • difficulty breathing,
  • swelling of the face, lips, tongue, or throat,
  • loss of appetite,
  • vomiting,
  • diarrhea,
  • stomach bloating,
  • blood in the urine or stools,
  • more wet diapers than usual,
  • sweating or shivering,
  • weakness,
  • drowsiness, 
  • seizures
  • dizziness, 
  • mental/mood changes such as nervousness, agitation, 
  • shaking (tremor), and
  • fast/irregular heartbeat.

Rare side effects of Caffeine include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

What Other Drugs Interact with Caffeine?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Caffeine has severe interactions with the following drugs:
  • Caffeine has serious interactions with the following drugs:
  • Caffeine has moderate interactions with at least 166 other drugs.
  • Caffeine has minor interactions with at least 47 other drugs.

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist about all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions or concerns.

What Are Warnings and Precautions for Caffeine?


  • Hypersensitivity

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Caffeine?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Caffeine?”


  • May increase severity of fibrocystic breast disease, PMS, increase risk of bladder, ovary, colon & pancreatic cancer
  • Carefully monitor for the development of necrotizing enterocolitis
  • Not for use in patients with anxiety, agitation, or tremor
  • Caution in patients with a history of peptic ulcer, hepatic impairment, renal impairment, seizure disorder, or cardiovascular disease
  • Avoid use in symptomatic arrhythmias and/or palpitations
  • Administer therapy with caution in infants with impaired renal or hepatic function; serum concentrations of caffeine should be monitored and the dose adjusted to avoid toxicity in this population; may need to monitor serum concentrations of caffeine periodically throughout treatment to avoid toxicity
  • See Caffeine OD for caffeine content of specific foods & drinks

Pregnancy and Lactation

  • Use with caution if benefits outweigh risks during pregnancy (crosses the placenta, can remain in fetus/neonate 64-300 hr)
  • Lactation
    • Enters breast milk; use with caution 


Why do we sleep? See Answer
Medscape. Caffeine.

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