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Last reviewed on RxList: 9/22/2020
Atropen Side Effects Center

Medical Editor: John P. Cunha, DO, FACOEP

What Is AtroPen?

AtroPen (auto-injector atropine) Injection is an anticholinergic agent (muscarinic antagonist) used to treatment poisoning by organophosphorous nerve or carbamate insecticides. The AtroPen auto-injector should be used only by persons trained to recognize and treat nerve agent or insecticide intoxication. AtroPen is intended as an initial treatment of symptoms of insecticide or nerve agent poisonings (i.e., breathing difficulties due to increased secretions); definitive medical care should be sought immediately. AtroPen should be administered as soon as symptoms of poisoning appear (usually tearing, excessive oral secretions, wheezing, muscle fasciculations, etc.).

What Are Side Effects of AtroPen?

Common side effects of AtroPen include:

  • pain at the injection site,
  • dry mouth,
  • blurred vision,
  • sensitivity to light,
  • confusion,
  • headache,
  • dizziness,
  • rapid or irregular heart rate,
  • flushing,
  • urinary problems,
  • constipation,
  • bloating,
  • nausea,
  • vomiting,
  • loss of sex drive,
  • impotence,
  • heat intolerance, and
  • hypersensitivity reactions such as skin rash.

Dosage for AtroPen?

Different dose strengths of the AtroPen are available depending on the recipient's age and weight. In moderate to severe poisoning, the administration of more than one AtroPen may be required until atropinization is achieved.

What Drugs, Substances, or Supplements Interact with AtroPen?

AtroPen may interact with pralidoxime, and barbiturates. Tell your doctor all medications and supplements you use.

AtroPen During Pregnancy and Breastfeeding

During pregnancy, AtroPen should be used only if prescribed. This drug passes into breast milk in trace amounts. Consult your doctor before breastfeeding.

Additional Information

Our AtroPen (auto-injector atropine) Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

This is not a complete list of side effects and others may occur. Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.


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Atropen Consumer Information
SIDE EFFECTS: Consult your pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

Read the entire patient information overview for Atropen (Atropine)


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Atropen Professional Information


Mild to moderate pain may be experienced at the site of injection.

The major and most common side effects of atropine can be attributed to its antimuscarinic action. These include dryness of the mouth, blurred vision, photophobia, confusion, headache, dizziness, tachycardia, palpitations, flushing, urinary hesitance or retention, constipation, abdominal distention, nausea, vomiting, loss of libido and impotency. Anhidrosis may produce heat intolerance and impairment of temperature regulation especially in a hot environment. Larger or toxic doses may produce such central effects as restlessness, tremor, fatigue, locomotor difficulties, delirium, followed by hallucinations, depression and ultimately, medullary paralysis and death. Large doses can also lead to circulatory collapse. In such cases, blood pressure declines and death due to respiratory failure may ensue following paralysis and coma. Hypersensitivity reactions will occasionally occur with atropine: these are usually seen as skin rashes, on occasion progressing to exfoliation. Adverse events seen in pediatrics are similar to those that occur in adult patients although central nervous system complaints are often seen earlier and at lower doses.

When atropine and pralidoxime are used together, the signs of atropinization may occur earlier than might be expected than when atropine is used alone. This is especially true if the total dose of atropine has been large and the administration of pralidoxime has been delayed. Excitement and manic behavior immediately following recovery of consciousness have been reported in several cases. However, similar behavior has occurred in cases of organophosphate poisoning that were not treated with pralidoxime.

Amitai et el (JAMA 1990) evaluated the safety of AtroPen® (atropine) 0.5 mg, 1 mg and 2 mg in a case series of 240 children who received AtroPen® (atropine) inappropriately (i.e., no nerve agent exposure) during the 1990 Gulf War Period. Overall, severity of atropinization followed a nonlinear correlation with dose. Estimated doses up to 0.045 mg/kg produced no signs of atropinization. Estimated doses between 0.045 mg/kg to 0.175 mg/kg and even greater than 0.175 mg/kg were associated with mild and severe effects respectively. Actual dosage received by children may have been considerably lower than estimated since incomplete injection in many cases was suspected. Regardless, adverse events reported were generally mild and self-limited. Few children required hospitalization. Adverse reactions reported were dilated pupils (43%), tachycardia (39%), dry membranes (35%), flushed skin (20%), temperature 37.8° C or 100° F (4%) and neurologic abnormalities (5%). There was also local pain and swelling. In 91 children with ECGs, no abnormalities were noted other than sinus tachycardia; 22 children had severe tachycardia of 160-190 bpm. Neurologic abnormalities consisted of irritability, agitation, confusion, lethargy, and ataxia.

The following adverse reactions were reported in published literature for atropine in both adults and children:

Cardiovascular: Sinus tachycardia, supraventricular tachycardia, junctional tachycardia, ventricular tachycardia, bradycardia, palpitations, ventricular arrhythmia, ventricular flutter, ventricular fibrillation, atrial arrhythmia, atrial fibrillation, atrial ectopic beats, ventricular premature contractions, bigeminal beats, trigeminal beats, nodal extrasystole, ventricular 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, decreased blood pressure, labile blood pressure, weak or impalpable peripheral pulses.

Eye: Mydriasis, blurred vision, pupils poorly reactive to light, photophobia, decreased contrast sensitivity, decreased visual acuity, decreased accommodation, cycloplegia, strabismus, heterophoria, cyclophoria, acute angle closure glaucoma, conjunctivitis, keratoconjunctivitis sicca, blindness, tearing, dry eyes/dry conjunctiva, irritated eyes, crusting of eyelid, blepharitis.

Gastrointestinal: Nausea, abdominal pain, paralytic ileus, decreased bowel sounds, distended abdomen, vomiting, delayed gastric emptying, decreased food absorption, dysphagia.

General:Hyperpyrexia, lethargy, somnolence, chest pain, excessive thirst, weakness, syncope, insomnia, tongue chewing, dehydration, feeling hot, injection site reaction.

Immunologic: Anaphylactic reaction.

Special Investigations: Leukocytosis, hyponatremia, elevated BUN, elevated hemoglobin, elevated erythrocytes, low hemoglobin, hypoglycemia, hyperglycemia, hypokalemia, increase in photic stimulation on EEG, signs of drowsiness on EEG, runs of alpha waves on EEG, alpha waves (EEG) blocked upon opening eyes.

Metabolic: Failure to feed.

Central Nervous System: Ataxia, hallucinations (visual or aural), seizures (generally tonic clonic), abnormal movements, coma, confusion, stupor, dizziness, amnesia, headache, diminished tendon reflexes, hyperreflexia, muscle twitching, opisthotnos, Babinski's reflex/Chaddock's reflex, hypertonia, dysmetria, muscle clonus, sensation of intoxication, difficulty concentrating, vertigo, dysarthria.

Psychiatric: Agitation, restlessness, delirium, paranoia, anxiety, mental disorders, mania, withdrawn behavior, behavior changes.

Genitourinary: Difficulty in micturation, urine urgency distended urinary bladder, urine retention, bed-wetting.

Pulmonary: Tachypnea, slow respirations, shallow respirations, breathing difficulty, labored respirations, inspiratory stridor, laryngitis, laryngospasm, pulmonary edema, respiratory failure, subcostal recession.

Dermatologic: Dry mucous membranes, dry warm skin, flushed skin, oral lesions, dermatitis, petechiae rash, macular rash papular rash, maculopapular rash, scarlatiniform rash, erythematous rash, sweating/moist skin, cold skin, cyanosed skin, salivation.

Drug Abuse And Dependence

Atropine possesses no known potential for dependence.

Read the entire FDA prescribing information for Atropen (Atropine)

Related Resources for Atropen

© Atropen Patient Information is supplied by Cerner Multum, Inc. and Atropen Consumer information is supplied by First Databank, Inc., used under license and subject to their respective copyrights.


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