sinus tachycardia
Orthostatic hypotension
Hypotension
Swollen tongue
Dysphagia (difficulty swallowing)
Glossodynia
Oral paraesthesiaRare (0.01-0.1% incidence) adverse effects include:

Neuroleptic malignant syndrome (Combination of fever, muscle stiffness, faster breathing, sweating, reduced consciousness, and sudden change in blood pressure and heart rate)
Tardive dyskinesia
Speech disturbance
Rhabdomyolysis
Angioedema
Blood dyscrasias such as agranulocytosis, leukopenia and neutropenia
Accommodation disorder
Pulmonary embolism
Gynaecomastia
GalactorrhoeaUnknown incidence adverse effects

Allergic reaction
Restless legs syndrome
Nausea
Oral mucosal lesions (ulcerations, blistering and inflammation)
Salivary hypersecretion
HyperprolactinaemiaAsenapine seems to have a relatively low weight gain liability for an atypical antipsychotic (which are notorious for their metabolic side effects) and a 2013 meta-analysis found significantly less weight gain (SMD [standard mean difference in weight gained in those on placebo vs. active drug]: 0.23; 95% CI: 0.07-0.39) than, paliperidone (SMD: 0.38; 95% CI: 0.27-0.48), risperidone (SMD: 0.42; 95% CI: 0.33-0.50), quetiapine (SMD: 0.43; 95% CI: 0.34-0.53), sertindole (SMD: 0.53; 95% CI: 0.38-0.68), chlorpromazine (SMD: 0.55; 95% CI: 0.34-0.76), iloperidone (SMD: 0.62; 95% CI: 0.49-0.74), clozapine (SMD: 0.65; 95% CI: 0.31-0.99), zotepine (SMD: 0.71; 95% CI: 0.47-0.96) and olanzapine (SMD: 0.74; 95% CI: 0.67-0.81) and approximately (that is, no statistically significant difference at the p=0.05 level) as much as weight gain as aripiprazole (SMD: 0.17; 95% CI: 0.05-0.28), lurasidone (SMD: 0.10; 95% CI: –0.02-0.21), amisulpride (SMD: 0.20; 95% CI: 0.05-0.35), haloperidol (SMD: 0.09; 95% CI: 0.00-0.17) and ziprasidone (SMD: 0.10; 95% CI: –0.02-0.22). Its potential for elevating plasma prolactin levels seems relatively limited too according to this meta-analysis.
This meta-analysis also found that asenapine has approximately the same odds ratio (3.28; 95% CI: 1.37-6.69) for causing sedation [compared to placebo-treated patients] as olanzapine (3.34; 95% CI: 2.46-4.50]) and haloperidol (2.76; 95% CI: 2.04-3.66) and a higher odds ratio (although not significantly) for sedation than aripiprazole (1.84; 95% CI: 1.05-3.05), paliperidone (1.40; 95% CI: 0.85-2.19) and amisulpride (1.42; 95% CI: 0.72 to 2.51) to name a few and is hence a mild-moderately sedating antipsychotic. The same meta-analysis suggested that asenapine had a relatively high risk of extrapyramidal symptoms compared to other atypical antipsychotics but a lower risk than first-generation or typical antipsychotics. Discontinuation
For all antipsychotics, the British National Formulary recommends a gradual dose reduction when discontinuing to avoid acute withdrawal syndrome or rapid relapse. Symptoms of withdrawal commonly include nausea, vomiting, and loss of appetite. Other symptoms may include restlessness, increased sweating, and trouble sleeping. Less commonly there may be a feeling of the world spinning, numbness, or muscle pains. Symptoms generally resolve after a short period of time.There is tentative evidence that discontinuation of antipsychotics can result in psychosis. It may also result in recurrence of the condition that is being treated. Rarely tardive dyskinesia can occur when the medication is stopped.