Methallylescaline

Coronary artery disease, Uncontrolled hypertension, Heart failure, Arrhythmia

MAL produces cardiovascular stimulation including tachycardia and hypertension, documented in a case report at 130 mg oral. Mescaline, the parent compound, increases blood pressure in controlled trials. Individuals with pre-existing cardiovascular disease or uncontrolled hypertension face elevated risk of adverse cardiac events.

Current lithium therapy

Lithium combined with serotonergic psychedelics has been associated with seizures in case reports across the class. No MAL-specific data exist, but the combination is considered contraindicated based on established class-level warnings.

Schizophrenia, Schizoaffective disorder, Bipolar disorder with psychotic features, Family history of schizophrenia-spectrum disorders

All serotonergic psychedelics carry risk of precipitating psychotic episodes in vulnerable individuals. MAL's potent 5-HT2A full agonism (EC50 79 nM, 85% efficacy) places it squarely within this risk class. No MAL-specific psychosis cases have been published, but the mechanism is well-established across the psychedelic class.

Cirrhosis, Severe hepatic impairment, Acute hepatitis

MAL depends on hepatic CYP-mediated metabolism for clearance. Impaired liver function could reduce clearance and increase exposure, potentially intensifying and prolonging effects. No clinical data exist to characterize the magnitude of this risk.

Pregnancy, Breastfeeding

No reproductive toxicity or teratogenicity studies have been conducted for MAL. In the absence of safety data, pregnancy and breastfeeding are contraindicated on precautionary grounds, consistent with all serotonergic psychedelics.

Concurrent use of irreversible MAOIs (phenelzine, tranylcypromine), Concurrent use of reversible MAOIs (moclobemide), Concurrent use of ayahuasca or harmine/harmaline

The combination of MAOIs with serotonergic psychedelics carries risk of serotonin toxicity (Malcolm & Thomas 2022). Phenethylamines are MAO-A substrates; MAOI co-administration would potentiate and prolong MAL's effects while increasing serotonin syndrome risk. This combination is contraindicated.

Concurrent fluoxetine, Concurrent paroxetine, Concurrent bupropion, Concurrent ketoconazole, Concurrent ritonavir, Concurrent grapefruit juice (large quantities)

Pharmacokinetic drug-drug interactions are predicted based on MAL's CYP2D6 and CYP3A4 metabolism. Inhibitors of these enzymes may increase MAL plasma concentrations and prolong effects. The clinical significance has not been studied.