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Neostigmine Side Effects

Medically reviewed by Last updated on Apr 1, 2023.

Applies to neostigmine: injection solution.

Serious side effects of Neostigmine

Along with its needed effects, neostigmine 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 while taking neostigmine:

More common

  • Blurred or loss of vision
  • chest pain, discomfort, or tightness
  • confusion
  • difficult or labored breathing
  • dizziness, faintness, or lightheadedness when getting up from a lying or sitting position suddenly
  • fast, slow, pounding, or irregular heartbeat or pulse
  • lightheadedness, dizziness, or fainting
  • sweating
  • twitches of the muscle visible under the skin
  • unusual tiredness or weakness

Incidence not known

  • Changes in patterns and rhythms of speech
  • cough
  • difficulty in moving
  • difficulty swallowing
  • disturbed color perception
  • double vision
  • halos around lights
  • hives
  • irregular, fast or slow, or shallow breathing
  • itching
  • loss of consciousness
  • muscle cramps and spasms
  • muscle pain or stiffness
  • night blindness
  • no blood pressure or pulse
  • noisy breathing
  • overbright appearance of lights
  • pain in the joints
  • pale or blue lips, fingernails, or skin
  • puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
  • seizures
  • skin rash
  • slurred speech
  • stopping of the heart
  • trouble in speaking
  • tunnel vision
  • unconsciousness

Get emergency help immediately if any of the following symptoms of overdose occur while taking neostigmine:

Symptoms of Overdose

Other side effects of Neostigmine

Some side effects of neostigmine 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

  • Bleeding, blistering, burning, coldness, discoloration of skin, feeling of pressure, hives, infection, inflammation, itching, lumps, numbness, pain, rash, redness, scarring, soreness, stinging, swelling, tenderness, tingling, ulceration, or warmth at site
  • drowsiness
  • headache
  • increased watering of the mouth
  • nausea
  • sleeplessness
  • sore throat
  • trouble sleeping
  • unable to sleep
  • vomiting

Incidence not known

  • Bloated
  • constricted, pinpoint, or small pupils (black part of eye)
  • diarrhea
  • dry mouth
  • excess air or gas in the stomach or intestines
  • feeling of warmth
  • full feeling
  • increase in mucous from the lungs
  • increased need to urinate
  • increased sweating
  • passing gas
  • passing urine more often
  • redness of the face, neck, arms and occasionally, upper chest
  • redness of the skin
  • skin rash
  • stomach cramps

For Healthcare Professionals

Applies to neostigmine: compounding powder, injectable solution, intravenous solution, oral tablet.


Frequency not reported: Bradycardia, tachycardia, decreased cardiac conduction (in severe cases possibly leading to heart block or cardiac arrest), hypotension, syncope[Ref]


Frequency not reported: Hyperhidrosis, rash, urticaria, pruritus[Ref]


Frequency not reported: Nausea, vomiting, diarrhea, abdominal cramps, flatulence, dry mouth, salivary hypersecretion, increased intestinal motility (which may result in involuntary defecation)[Ref]


Frequency not reported: Urinary incontinence[Ref]


Frequency not reported: Hypersensitivity, angioedema, anaphylactic reaction[Ref]


Frequency not reported: Muscle spasm, muscle cramps, fasciculation[Ref]

Nervous system

Frequency not reported: Cholinergic syndrome (especially at high doses; in patients with myasthenia gravis, cholinergic crisis may be difficult to distinguish from myasthenia crisis), headache, dizziness, convulsions, loss of consciousness, coma, drowsiness, restlessness, ataxia, slurred speech, general weakness, paralysis[Ref]


Frequency not reported: Miosis, lacrimation increased, vision changes, nystagmus[Ref]


Frequency not reported: Increased bronchial secretion, bronchospasm, dyspnea, respiratory depression, respiratory arrest, tight chest, wheezing[Ref]


Frequency not reported: Agitation, fear, insomnia[Ref]


1. Cerner Multum, Inc. UK Summary of Product Characteristics.

2. Cerner Multum, Inc. Australian Product Information.

3. Product Information. Neostigmine Methyl Sulfate (neostigmine). American Regent Laboratories Inc. 2019.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Some side effects may not be reported. You may report them to the FDA.