AtroPen Side Effects

Generic name: atropine

Medically reviewed by Drugs.com. Last updated on Mar 19, 2025.

Note: This document provides detailed information about AtroPen Side Effects associated with atropine. Some dosage forms listed on this page may not apply specifically to the brand name AtroPen.

Applies to atropine: intramuscular solution.

Serious side effects of AtroPen

Along with its needed effects, atropine (the active ingredient contained in AtroPen) 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 while taking atropine:

More common side effects

• bigger, dilated, or enlarged pupils
• blindness
• blurred vision
• chest pain, discomfort, or tightness
• cough
• decreased vision
• decrease in urine volume
• decrease in frequency of urination
• difficulty in passing urine
• difficulty swallowing
• dizziness
• eye pain
• extremely high fever or body temperature
• fainting
• fast, shallow breathing
• fast, slow, or irregular heartbeat
• fast, weak heartbeat
• headache
• hives, itching, skin rash
• increase in mucous from lungs
• lightheadedness
• muscle cramps
• nausea or vomiting
• pain at the injection site
• painful urination
• pale, clammy skin
• pounding or rapid pulse
• puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
• stomach pain
• tearing
• thirst
• trouble breathing
• unusual tiredness or weakness

Less common side effects

• decreased awareness or responsiveness
• dryness or soreness of the throat
• excessive muscle tone
• hoarseness
• loss of memory
• muscle stiffness, tension, or tightness
• overactive reflexes
• problems with memory
• seizures
• severe sleepiness
• shakiness and unsteady walk
• unsteadiness, trembling or other problems with muscle control or coordination
• voice changes

Incidence not known

• change in color vision
• confusion
• difficulty seeing at night
• discouragement
• dry eyes
• dry mouth
• feeling sad or empty
• hallucinations
• holding false beliefs that cannot be changed by fact
• increased sensitivity of the eyes to sunlight
• lack of appetite
• loss of interest or pleasure
• shakiness in the legs, arms, hands, or feet
• trembling or shaking of the hands or feet
• trouble concentrating
• trouble sleeping
• unusual excitement, nervousness, or restlessness

Other side effects of AtroPen

Some side effects of atropine 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:

Incidence not known

• bloating
• constipation
• diarrhea
• impotence
• loss of libido
• small or red spots on the skin

For healthcare professionals

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

General adverse events

Although individual reactions vary greatly, systemic doses are likely to produce the following effects:

0.5 mg: Slight dryness of the nose and mouth, bradycardia

1 mg: Greater dryness of nose and mouth with thirst; slowing, then acceleration of the heart; slight mydriasis

2 mg: Very dry mouth, tachycardia with palpitations, mydriasis, slight blurring of near vision

5 mg: Increase in the above symptoms plus disturbance of speech, difficulty swallowing, headache, hot, dry skin, restlessness with asthenia

10 mg and over: Above symptoms to extreme degrees, plus ataxia, excitement, disorientation, hallucinations, delirium, and coma

65 mg: May be fatal^[Ref]

Cardiovascular

• Common (1% to 10%): Tachycardia (arrhythmias, transient exacerbation of bradycardia)
• Very rare (less than 0.01%): Atrial arrhythmias, ventricular fibrillation, angina, hypertensive crisis
• Frequency not reported: Bradycardia, slowing then acceleration of heart, palpitations, circulatory collapse, blood pressure declines, sinus tachycardia, supraventricular tachycardia, junctional tachycardia, ventricular tachycardia, ventricular flutter, ventricular fibrillation, atrial arrhythmia, atrial fibrillation, atrial ectopic beats, ventricular premature contractions, bigeminal beats, trigeminal beats, nodal extrasystole, supraventricular extrasystole, asystole, cardiac syncope, prolongation of sinus node recovery time, cardiac dilation, left ventricular failure, myocardial infarction, intermittent nodal rhythm (no P wave), prolonged P wave, shortened PR segment, R on T phenomenon, shortened RT duration, widening and flattening of QRS complex, prolonged QT interval, flattening of T wave, repolarization abnormalities, altered ST-T waves, retrograde conduction, transient AV dissociation, increased blood pressure, labile blood pressure, weak or impalpable peripheral pulses, paradoxical atrioventricular block^[Ref]

Nervous system

• Very common (10% or more): Loss of taste
• Common (1% to 10%): Incoordination
• Uncommon (0.1% to 1%): Seizure, drowsiness
• Frequency not reported: Disturbance of speech, headache, asthenia, ataxia, coma, dizziness, tremor, locomotor difficulties, medullary paralysis, neurological abnormalities, lethargy, somnolence, syncope, runs of alpha waves on EEG, alpha waves (EEG) blocked upon opening eyes, seizures (generally tonic-clonic), abnormal movements, stupor, amnesia, diminished tendon reflexes, hyperreflexia, opisthotonos, Babinski's reflex/Chaddock's reflex, hypertonia, dysmetria, muscle clonus, sensation of intoxication, difficulty concentrating, vertigo, dysarthria, loss of taste, giddiness, staggering^[Ref]

Ocular

• Very common (10% or more): Visual disturbances (mydriasis, inhibition of accommodation, blurred vision, photophobia)
• Frequency not reported: Blurring of near vision, pupils poorly reactive to light, decreased contrast sensitivity, decreased visual acuity, cycloplegia, strabismus, heterophoria, cyclophoria, acute angle closure glaucoma, conjunctivitis, keratoconjunctivitis sicca, blindness, tearing, dry eyes/dry conjunctiva, irritated eyes, crusting of eyelids, blepharitis, increase in photic stimulation on EEG, increase in intraocular pressure^[Ref]

Gastrointestinal

• Very common (10% or more): Dryness of mouth (difficulty swallowing and talking, thirst), parasympathetic inhibition of gastrointestinal tract (constipation and reflux), inhibition of gastric secretion, nausea, vomiting, bloated feeling
• Frequency not reported: Abdominal distension, abdominal pain, paralytic ileus, decreased bowel sounds, delayed gastric emptying, decreased food absorption, dysphagia, retrosternal pain due to gastric reflux^[Ref]

Dermatologic

• Very common (10% or more): Anhidrosis, urticaria, rash
• Common (1% to 10%): Flushing
• Frequency not reported: Dry skin, hot skin, scarlatiniform rash, skin rashes, exfoliation, dry mucus membranes, warm skin, maculopapular rash, erythematous rash, sweating/moist skin, cold skin, cyanosed skin, salivation^[Ref]

Psychiatric

• Common (1% to 10%): Excitement, confusion, hallucinations
• Uncommon (0.1% to 1%): Psychotic reactions
• Frequency not reported: Restlessness, disorientation, delirium, loss of libido, delirium, depression, manic behavior, irritability, agitation, insomnia, agitation, paranoia, anxiety, mental disorders, mania, withdrawn behavior, behavior changes, nervousness^[Ref]

Other

• Common (1% to 10%): Hyperthermia
• Frequency not reported: Death, fever, heat intolerance, impairment of temperature regulation (especially in a hot environment), fatigue, hyperpyrexia, chest pain, weakness, feeling hot, signs of drowsiness on EEG^[Ref]

Genitourinary

• Common (1% to 10%): Inhibition of parasympathetic control of the urinary bladder, urinary retention
• Frequency not reported: Urinary hesitancy, impotency, difficulty in micturition, urine urgency, distended urinary bladder, bed wetting^[Ref]

Hypersensitivity

• Rare (less than 0.1%): Allergic reactions
• Very rare (less than 0.01%): Anaphylaxis
• Frequency not reported: Hypersensitivity^[Ref]

Respiratory

• Frequency not reported: Dryness of nose, respiratory failure, tachypnea, slow respirations, shallow respirations, inspiratory stridor, laryngitis, laryngospasm, pulmonary edema, subcostal recession, reduced bronchial secretions, formation of bronchial plugs^[Ref]

Metabolic

• Frequency not reported: Thirst, excessive thirst, dehydration, hyponatremia, hypokalemia, hypoglycemia, hyperglycemia^[Ref]

Musculoskeletal

• Frequency not reported: Muscle twitching^[Ref]

Local

• Frequency not reported: Pain at injection site, local swelling, injection site reaction, redness or other signs of irritation at the injection site^[Ref]

Hematologic

• Frequency not reported: Leukocytosis, elevated hemoglobin, elevated erythrocytes, low hemoglobin^[Ref]

Renal

• Frequency not reported: Elevated BUN^[Ref]

Further information

AtroPen side effects can vary depending on the individual. Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.

Note: Medication side effects may be underreported. If you are experiencing side effects that are not listed, submit a report to the FDA by following this guide.

Medical Disclaimer