Atropine
Contraindicated
Textbook
Their antimuscarinic action is likely to intensify the toxicity of atropine poisoning.
Phenothiazines should not be used in atropine poisoning.
Source: G&G 14e · p218
Drug reference
phenothiazines
Antipsychotic
Antipsychotic
CDSCO approved
EXCRETION
—
not curated
INTERACTIONS
4 major
incl. contraindicated
PREGNANCY
—
not curated
Top interactionssee all 9 →
- AtropineContraindicatedTextbookG&G 14e · p218
- ArtemisininsSevereTextbookKDT 7e · p816-835
- LevodopaSevereTextbookKDT 7e · p429
- PhysostigmineSevereTextbookKDT 7e · p110
Mechanism
Not yet extracted
Side effects
Common
dystonic reactions (more common in children)chronic and low grade phototoxic photosensitivityparkinsonism (drug induced disease)
Serious
- CNS depression (increased in renal failure)
Drug interactions
Artemisinins
Severe
Textbook
Increased risk of cardiac conduction defects.
Source: KDT 7e · p816-835
Levodopa
Severe
Textbook
Reverse the therapeutic effect of levodopa.
Avoid co-administration.
Source: KDT 7e · p429
Physostigmine
Severe
Textbook
Partial antagonism of overdose symptoms and coma; however, it may worsen the fall in BP and arrhythmias.
Use is risky.
Source: KDT 7e · p110
Antacids
Moderate
Textbook
Decreased absorption of phenothiazines.
Stagger administration of antacids and phenothiazines by 2 hours.
Source: KDT 7e · p656
First Generation H1 Antihistaminics
Moderate
Textbook
Increased anticholinergic side effects (dry mouth, altered bowel movement, urinary hesitancy, blurring of vision).
Monitor for increased anticholinergic effects.
Source: KDT 7e
Intravenous Anaesthetics
Moderate
Textbook
Delirium, convulsions, and other excitatory effects during recovery from intravenous anaesthetics.
Excitatory effects are generally suppressed by opioids.
Source: KDT 7e · p385
Sulfonylureas
Moderate
Textbook
Reduced glucose-lowering effect of sulfonylureas.
Source: G&G 14e · p1034
Trihexyphenidyl
Moderate
Database
Additive anticholinergic effects; phenothiazines have intrinsic anticholinergic activity
Monitor for anticholinergic toxicity
Source: Kimi deep-research + Cla
Related guidelines
Other Unclassified drugs
Ask House about phenothiazines
Continue into a citation-backed clinical answer with the drug context already attached.
Sources: KD Tripathi 7e·Verified: 2026-05-10 · House clinical team