Medical Editor: John P. Cunha, DO, FACOEP Last updated on RxList: 10/6/2021

Drug Summary

Last reviewed on RxList 10/31/2018

Donnatal (belladonna alkaloids, phenobarbital) is a combination of an anticholinergic/antispasmodic drug and a barbiturate sedative used to treat abdominal pain, bloating and cramps in patients with irritable bowel syndrome. Donnatal is also used to treat acute inflammation of the stomach and intestines (gastroenteritis) to reduce pain and diarrhea, and in patients with duodenal ulcer. Donnatal is available in generic form. Common side effects of Donnatal include:

  • dizziness,
  • drowsiness,
  • weakness,
  • blurred vision,
  • dry eyes,
  • dry mouth,
  • nausea,
  • vomiting,
  • constipation,
  • abdominal bloating,
  • increased sensitivity to light,
  • decreased taste sensation,
  • decreased sweating or urination,
  • headache,
  • sleep problems (insomnia),
  • restlessness,
  • excitability,
  • impotence,
  • loss of interest in sex, or
  • trouble having an orgasm.

Tell your doctor if you have unlikely but serious side effects of Donnatal including:

  • dry/hot/flushed skin,
  • fast or irregular heartbeat,
  • loss of coordination,
  • slurred speech,
  • fainting,
  • mental/mood changes (such as confusion, agitation, unusual excitement, depression, rare thoughts of suicide),
  • difficulty urinating, or
  • slow or shallow breathing.

The dosage of Donnatal is adjusted to individual patients for symptomatic control with minimum adverse reactions. The usual dose is one tablet every 8 or 12 hours as prescribed. Products that may interact with Donnatal include blood thinners, ketoconazole, MAO inhibitors, bronchodilators, bladder or urinary medications or irritable bowel medications. Hormonal birth control products (pills, patch, ring) may not be effective if taken with Donnatal. Discuss all medications you are taking with your doctor. Donnatal is not recommended for use during pregnancy. It may harm a fetus. Consult your doctor. This medication passes into breast milk and may have undesirable effects on a nursing infant. Consult your doctor before breastfeeding. Donnatal may cause withdrawal symptoms (anxiety, muscle twitching, shakiness, dizziness, worsening weakness, nausea, vomiting) if you suddenly stop using it. Withdrawal from phenobarbital can be severe and include seizures or death.

Our Donnatal Side Effects Drug Center provides a comprehensive view of available drug information on the potential side effects when taking this medication.

Drug Description


Each Donnatal Extentabs® (belladonna alkaloids, phenobarbital) tablet contains:

Phenobarbital, USP (3/4 gr.) ................................ 48.6 mg
Hyoscyamine Sulfate, USP ................................... 0.3111 mg
Atropine Sulfate, USP ............................................ 0.0582 mg
Scopolamine Hydrobromide, USP ...................... 0.0195 mg

Each Donnatal Extentabs® (belladonna alkaloids, phenobarbital) tablet contains the equivalent of three Donnatal® tablets. Extentabs® are designed to release the ingredients gradually to provide effects for up to twelve (12) hours.

In addition, each tablet contains the following inactive ingredients: Anhydrous Lactose, Calcium Sulfate Granular, Colloidal Silicon Dioxide, Dibasic Calcium Phosphate, Lactose Monohydrate, Magnesium Stearate, and Stearic Acid. Film Coating and Polishing Solution contains: D&C Yellow #10 Aluminum Lake, FD&C Blue #1 Aluminum Lake, Hydroxypropyl Methylcellulose, Polydextrose, Polyethylene Glycol, Titanium Dioxide, and Triacetin. The printing ink contains Titanium Dioxide.



Based on a review of this drug by the National Academy of Sciences - National Research Council and/or other information, FDA has classified the following indications as "possibly" effective:

For use as adjunctive therapy in the treatment of irritable bowel syndrome (irritable colon, spastic colon, mucous colitis) and acute enterocolitis.




The dosage of Donnatal Extentabs® (belladonna alkaloids, phenobarbital) should be adjusted to the needs of the individual patient to assure symptomatic control with a minimum of adverse reactions. The usual dose is one tablet every twelve (12) hours. If indicated, one tablet every eight (8) hours may be given.


Donnatal Extentabs® (belladonna alkaloids, phenobarbital) Tablets are supplied as: film coated green, round, compressed tablets printed "P421" in black ink.

  • Bottles of 100 tablets
  • Bottles of 500 tablets

Store at 20-25°C (68-77°F) [See USP Controlled Room Temperature]. Protect from light and moisture.

Dispense in a well-closed, light-resistant container as defined in the USP using a child-resistant closure.

Also available: Donnatal® Tablets in bottles of 100 and 1000 tablets and Donnatal® Elixir in 4 fl oz bottles and 1 pint bottles.

PBM Pharmaceuticals, Inc. Gordonsville, VA 22942. FDA Rev date: n/a

Side Effects & Drug Interactions


Adverse reactions may include xerostomia; urinary hesitancy and retention; blurred vision; tachycardia; palpitation; mydriasis; cycloplegia; increased ocular tension; loss of taste sense; headache; nervousness; drowsiness; weakness; dizziness: insomnia; nausea; vomiting; impotence; suppression of lactation; constipation; bloated feeling; musculoskeletal pain; severe allergic reaction or drug idiosyncrasies, including anaphylaxis, urticaria and other dermal manifestations; and decreased sweating. Elderly patients may react with symptoms of excitement, agitation, drowsiness, and other untoward manifestations to even small doses of the drug.

Phenobarbital may produce excitement in some patients, rather than a sedative effect. In patients habituated to barbiturates, abrupt withdrawal may produce delirium or convulsions.


No information provided.



In the presence of a high environmental temperature, heat prostration can occur with belladonna alkaloids (fever and heatstroke due to decreased sweating).

Diarrhea may be an early symptom of incomplete intestinal obstruction, especially in patients with ileostomy or colostomy. In this instance treatment with this drug would be inappropriate and possibly harmful.

Donnatal Extentabs® (belladonna alkaloids, phenobarbital) may produce drowsiness or blurred vision. The patient should be warned, should these occur, not to engage in activities requiring mental alertness, such as operating a motor vehicle or other machinery, and not to perform hazardous work.

Phenobarbital may decrease the effect of anticoagulants and necessitate larger doses of the anticoagulant for optimal effect. When phenobarbital is discontinued, the dose of the anticoagulant may have to be decreased.

Phenobarbital may be habit forming and should not be administered to individuals known to be addiction prone or to those with a history of physical and/or psychological dependence upon drugs.

Since barbiturates are metabolized in the liver, they should be used with caution and initial doses should be small in patients with hepatic dysfunction.



Use with caution in patients with: autonomic neuropathy, hepatic or renal disease, hyperthyroidism, coronary heart disease, congestive heart failure, cardiac arrhythmias, tachycardia, and hypertension.

Belladonna alkaloids may produce a delay in gastric emptying (antral stasis) which would complicate the management of gastric ulcer.

Theoretically, with overdosage, a curare-like action may occur.

Carcinogenesis, mutagenesis: Long-term studies in animals have not been performed to evaluate c arcinogenic potential.

Pregnancy Category C: Animal reproduction studies have not been conducted with Donnatal Extentabs® (belladonna alkaloids, phenobarbital) . It is not known whether Donnatal Extentabs® (belladonna alkaloids, phenobarbital) can cause fetal harm when administered to a pregnant woman or can affect reproduction capacity. Donnatal Extentabs® (belladonna alkaloids, phenobarbital) should be given to a pregnant woman only if clearly needed.

Nursing mothers: It is not known whether this drug is excreted in human milk. Because many drugs are excreted in human milk, caution should be exercised when Donnatal Extentabs® (belladonna alkaloids, phenobarbital) is administered to a nursing mother.

Overdose & Contraindications


The signs and symptoms of overdose are headache, nausea, vomiting, blurred vision, dilated pupils, hot and dry skin, dizziness, dryness of the mouth, difficulty in swallowing, and CNS stimulation. Treatment should consist of gastric lavage, emetics, and activated charcoal. If indicated, parenteral cholinergic agents such as physostigmine or bethanechol chloride should be added.


Glaucoma, obstructive uropathy (for example, bladder neck obstruction due to prostatic hypertrophy); obstructive disease of the gastrointestinal tract (as in achalasia, pyloroduodenal stenosis, etc.); paralytic ileus, intestinal atony of the elderly or debilitated patient; unstable cardiovascular status in acute hemorrhage; severe ulcerative colitis especially if complicated by toxic megacolon; myasthenia gravis; hiatal hernia associated with reflux esophagitis.

Donnatal Extentabs® (belladonna alkaloids, phenobarbital) is contraindicated in patients with known hypersensitivity to any of the ingredients. Phenobarbital is contraindicated,in acute intermittent porphyria and in those patients in whom phenobarbital produces restlessness and/or excitement.

Clinical Pharmacology


ACTIONS: This drug combination provides natural belladonna alkaloids in a specific, fixed ratio combined with phenobarbital to provide peripheral anticholinergic/antispasmodic action and mild sedation.

Medication Guide


No information provided. Please refer to the WARNINGS and PRECAUTIONS sections.

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