Note: This document contains side effect information about aspirin / caffeine. Some dosage forms listed on this page may not apply to the brand name Alka-Seltzer Hangover Relief.

Applies to aspirin / caffeine: oral packet, oral tablet.

Serious side effects

WARNING/CAUTION: Even though it may be rare, some people may have very bad and sometimes deadly side effects when taking a drug. Tell your doctor or get medical help right away if you have any of the following signs or symptoms that may be related to a very bad side effect:

• Signs of an allergic reaction, like rash; hives; itching; red, swollen, blistered, or peeling skin with or without fever; wheezing; tightness in the chest or throat; trouble breathing, swallowing, or talking; unusual hoarseness; or swelling of the mouth, face, lips, tongue, or throat.
• Signs of bleeding like throwing up or coughing up blood; vomit that looks like coffee grounds; blood in the urine; black, red, or tarry stools; bleeding from the gums; abnormal vaginal bleeding; bruises without a cause or that get bigger; or bleeding you cannot stop.
• Signs of kidney problems like unable to pass urine, change in how much urine is passed, blood in the urine, or a big weight gain.
• Signs of liver problems like dark urine, feeling tired, not hungry, upset stomach or stomach pain, light-colored stools, throwing up, or yellow skin or eyes.
• Signs of high potassium levels like a heartbeat that does not feel normal; feeling confused; feeling weak, lightheaded, or dizzy; feeling like passing out; numbness or tingling; or shortness of breath.
• Signs of too much acid in the blood (acidosis) like confusion; fast breathing; fast heartbeat; a heartbeat that does not feel normal; very bad stomach pain, upset stomach, or throwing up; feeling very sleepy; shortness of breath; or feeling very tired or weak.
• Weakness on 1 side of the body, trouble speaking or thinking, change in balance, drooping on one side of the face, or blurred eyesight.
• Very bad dizziness or passing out.
• Very bad headache.
• Ringing in the ears, hearing loss, or any other changes in hearing.
• Feeling agitated.
• Seizures.
• A fast heartbeat.

Other side effects

All drugs may cause side effects. However, many people have no side effects or only have minor side effects. Call your doctor or get medical help if any of these side effects or any other side effects bother you or do not go away:

• Feeling nervous and excitable.
• Trouble sleeping.
• Stomach pain or heartburn.
• Upset stomach or throwing up.

These are not all of the side effects that may occur. If you have questions about side effects, call your doctor. Call your doctor for medical advice about side effects.

You may report side effects to the FDA at 1-800-332-1088. You may also report side effects at https://www.fda.gov/medwatch.

For Healthcare Professionals

Applies to aspirin/caffeine: oral powder for reconstitution, oral tablet, oral tablet effervescent.

General

The more commonly reported adverse events with aspirin have included gastrointestinal events such as nausea and dyspepsia; caffeine may cause nervousness, irritability, sleeplessness, and palpitations, especially with higher doses.^[Ref]

Gastrointestinal

Aspirin:

Very Common (10% or more): Epigastric distress (up to 83%)

Common (1% to 10%): Abdominal discomfort/pain, endoscopically identifiable gastric mucosal lesions, nausea, vomiting

Frequency not reported: Hemorrhage, peptic ulcers, perforation, esophageal ulcerations, dyspepsia, gastritis^[Ref]

Endoscopically identifiable gastric mucosal lesions occur in most patients who receive a single dose of aspirin. Clinically evident gastrointestinal bleeding has been reported in as many as 3% of treated elderly patients. Anorectal ulceration and rectal stenosis have been reported in patients who abuse aspirin-containing rectal suppositories.^[Ref]

Hematologic

Aspirin:

Frequency not reported: Predictable antiplatelet effects, hemorrhage, increased blood fibrinolytic activity, hypoprothrombinemia, thrombocytopenia, thrombocyturia, megaloblastic anemia, pancytopenia, aplastic anemia, ecchymosis

Hypersensitivity

Aspirin:

Very common (10% or more): Hypersensitivity reactions in asthmatics who are aspirin-sensitive (e.g., with the clinical triad of aspirin sensitivity, bronchial asthma, and nasal polyps)

Frequency not reported: Hypersensitivity reactions include bronchospasm, rhinitis, conjunctivitis, urticaria, angioedema, sin reactions, and anaphylaxis

Respiratory

Aspirin:

Frequency not reported: Bronchospasm (in patients sensitive to aspirin and other NSAID)

Renal

The mechanism of an aspirin-induced decrease in renal function may be related to inhibition of renal prostaglandin synthesis with consequent decreases in renal blood flow. Vasodilating renal prostaglandins may be particularly important in patients who exhibit arterial underfilling (i.e. heart failure, cirrhosis). The administration of high doses of NSAIDs to such patients has produced acute renal failure in rare instances.

Aspirin:

Frequency not reported: Renal dysfunction, renal failure, increased blood uric acid levels

Other

Aspirin:

Frequency not reported: Reye's syndrome, tinnitus, temporary hearing loss

Caffeine:

Frequency not reported: Fibrocystic breast disease

In one study of the effects of caffeine, 634 women with fibrocystic breast disease (compared to 1066 women without the disease), the occurrence of fibrocystic breast disease was positively associated with average daily consumption of caffeine. Women who consumed 31 to 250 mg/day of caffeine were reported to have a 1.5 times increase in odds to have the disease. Women who consumed over 500 mg/day of caffeine were reported to have a 2.3 times increase in odds

Dermatologic

Aspirin:

Frequency not reported: Stevens-Johnson syndrome, lichenoid eruption

Hepatic

Aspirin:

Frequency not reported: Hepatotoxicity, cholestatic hepatitis, aminotransferase elevations

Psychiatric

Caffeine:

Frequency not reported: Nervousness, irritability, sleeplessness (particularly in higher doses)

Nervous system

Aspirin:

Frequency not reported: Dizziness, headache

Caffeine:

Frequency not reported: Dizziness, tremor

Cardiovascular

Aspirin:

Frequency not reported: Salicylate-induced variant angina, ventricular ectopy, conduction abnormalities, and hypotension, particularly during salicylate toxicity

Caffeine:

Frequency not reported: Palpitations

Metabolic

Aspirin:

Frequency not reported: Dehydration, hyperkalemia, hypoglycemia, sodium and fluid retention, respiratory alkalosis and metabolic acidosis (particularly during salicylate toxicity)

Genitourinary

Aspirin:

Frequency not reported: Interstitial nephritis, papillary necrosis, proteinuria