The following side effects may get better over time as your body gets used to the medication. Let your healthcare provider know immediately if you continue to experience these symptoms or if they worsen over time.
Common Side Effects
- Indigestion or upset stomach (10%)
- Headache (9%)
- Sleepiness (9%)
- Nausea (8%)
- Dizziness (7%)
- Constipation (7%)
- Nervousness (6%)
- Weakness (5%)
- Swelling of legs or hands (5%)
Less Common Side Effects
- Vomiting
- Stomach pain
- Diarrhea
- Tremor or shakiness
- Confusion
- Sweating
- Itching
- Rash
Nalfon serious side effects
Contact your healthcare provider immediately if you experience any of the following.
- Liver problems: nausea, fatigue, diarrhea, yellowing of skin or whites of the eyes
- Kidney problems: irregular heartbeat, shortness of breath, lower urine output, confusion, weakness
- Heart attack: chest pain, sweating, shortness of breath, pain or discomfort in jaw, neck, or shoulders
- Gastrointestinal (GI) bleeding: black or tarry stool, dizziness, stomach pain or discomfort
- Serious allergic reactions: hives, swelling of face, tongue, or throat, difficulty breathing
- Serious skin reactions: flu-like symptoms, painful rash or blisters all over body, peeling of skin
- Stroke: weakness on one side of the body, slurred speech, loss of balance, confusion
- Heart failure: shortness of breath, swelling or fluid buildup in ankles, feet, or legs, cough
Source: DailyMed
The following Nalfon side effects have also been reported
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 immediately if any of the following side effects occur:
Less common
Abdominal or stomach pain
bloating or swelling of the face, arms, hands, lower legs, or feet
blurred vision
continuing ringing or buzzing or other unexplained noise in the ears
decreased hearing
difficult or labored breathing
fast, irregular, pounding, or racing heartbeat or pulse
hearing loss
itching skin or rash
rapid weight gain
tightness in the chest
tingling of the hands or feet
unusual weight gain or loss
Rare
Back, leg, or stomach pains
black or red, tarry stools
bleeding gums
blood in vomit
bloody or cloudy urine
bloody stools
burning feeling in the chest or stomach
chills
clay-colored stools
coughing up blood
dark urine
difficult, burning, or painful urination
difficulty with swallowing
dizziness
fever with or without chills
frequent urge to urinate
general body swelling
greatly decreased frequency or amount of urine
hoarseness
increased menstrual flow or vaginal bleeding
increased thirst
indigestion
large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or sex organs
loss of appetite
lower back or side pain
nosebleeds
not able to pass urine
pale skin
paralysis
pinpoint red or purple spots on the skin
prolonged bleeding from cuts
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
red or dark brown urine
redness of the skin
severe or continuing stomach pain
sores, ulcers, or white spots on the lips or in the mouth
stomach upset
swelling of the face, fingers, or lower legs
swelling of the hands, legs, and feet
swollen or painful glands
tenderness in the stomach area
troubled breathing
unpleasant breath odor
unusual bleeding or bruising
unusual tiredness or weakness
vomiting
vomiting of blood or material that looks like coffee grounds
yellow eyes or skin
Symptom of overdose
Dizziness, faintness, or lightheadedness when getting up suddenly from a lying or sitting position
irregular, fast or slow, or shallow breathing
pale or blue lips, fingernails, or skin
rapid, deep breathing
restlessness
shakiness and unsteady walk
stomach cramps
unsteadiness, trembling, or other problems with muscle control or coordination
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
More common
Acid or sour stomach
belching
headache
lack or loss of strength
sleepiness or unusual drowsiness
stomach discomfort
Less common
Body aches or pain
ear congestion
increased sweating
loss of voice
mood or mental changes
muscle aches
stuffy or runny nose
Rare
General feeling of discomfort or illness
trouble sleeping
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