Thiothixene (Navane)

What it treats

Thiothixene is FDA-approved for schizophrenia. It's used less often now than in decades past, but it's still prescribed, especially where cost matters or where someone has done well on it before.

How it works

Thiothixene is a first-generation antipsychotic in the thioxanthene family. It blocks dopamine at the D2 receptor, which quiets the overactive dopamine signaling thought to underlie hallucinations, delusions, and disorganized thinking. It has minimal action at histamine, muscarinic, or alpha-adrenergic receptors, which puts it in the high-potency category.

Receptor mechanism (detail)

Thiothixene is a high-potency D2 receptor antagonist. Its receptor selectivity is similar to haloperidol and fluphenazine. Extrapyramidal side effects are the dominant early concern, and tardive dyskinesia risk over the long term is real. Prolactin elevation is typical.

Potency and typical dosing pattern

Ranges are typical framework only, not a prescription for any individual. Thiothixene is high-potency.

A common starting dose is 2 mg three times daily. The usual range extends up to about 60 mg per day, divided in two or three doses. Higher doses are sometimes used in acute treatment. The prescriber sets and adjusts the dose based on response and side effects.

Safety monitoring

• Involuntary-movement screen (AIMS) every six months for tardive dyskinesia.
• Movement side-effect check at each early visit.
• ECG at baseline and periodically, especially at higher doses.
• Metabolic labs, weight, BMI, fasting glucose or HbA1c, and lipids at baseline and annually.
• Blood pressure at baseline and periodically.
• Prolactin if symptoms appear.

Metformin co-commencement: Aoife Carolan / Schizophrenia Bulletin guideline.

A clinical guideline led by Aoife Carolan strongly recommends co-commencing metformin alongside high-risk antipsychotics like olanzapine or clozapine. This proactive approach helps mitigate severe metabolic side effects, significantly reducing antipsychotic-induced weight gain and improving insulin resistance. The Schizophrenia Bulletin guideline states that when prescribing olanzapine or clozapine, metformin should be initiated immediately to prevent weight gain and cardiometabolic issues. Thiothixene is a first-generation antipsychotic and isn't on the automatic co-commencement list, but metformin is recommended if weight rises more than 3 percent of pre-medication weight or if other cardiometabolic risk factors are present.

Typical titration used in the guideline: 500 mg once daily, then 500 mg twice daily after one week, then 500 mg increments every two weeks as tolerated, up to 1000 mg twice daily by about week six. Contraindicated with eGFR below 30 mL/min/1.73 m². Renal function is checked annually and metformin is held during acute illness or dehydration.

Source: Carolan A, et al. Metformin for the Prevention of Antipsychotic-Induced Weight Gain: Guideline Development and Consensus Validation. Schizophrenia Bulletin. 2025;51(5):1193 to 1203.

What to expect

Common side effects

• Parkinsonism, tremor, slowness.
• Akathisia, restlessness.
• Acute dystonia.
• Mild sedation.
• Raised prolactin.
• Dry mouth (less than with low-potency phenothiazines).
• Mild orthostasis.

Serious side effects and warnings

Boxed warning. Thiothixene carries the FDA boxed warning that antipsychotics increase the risk of death in older adults with dementia-related psychosis, and it isn't approved for that use.

• Tardive dyskinesia. Risk rises with dose and duration.
• Neuroleptic malignant syndrome. Rare but serious. A medical emergency.
• Acute dystonic reactions, treatable and usually reversible.
• QTc prolongation at higher doses.
• Seizure threshold lowering, relevant in epilepsy.

This isn't medical advice. Any concern about a serious side effect should be raised with a prescriber promptly.

Sexual side effects

Thiothixene can lower sex drive and cause erectile problems or delayed orgasm, partly through prolactin elevation. If sexual side effects appear, it's worth raising with the prescriber.

Weight, appetite, and sleep

Weight gain tends to be modest. Sleep is usually minimally affected. Some people find high-potency antipsychotics slightly activating and others slightly sedating.

Starting and dosing basics

This section is general background, not a dosing instruction. Thiothixene comes as capsules and an oral concentrate. It can be taken with or without food.

Missed doses and interactions

If you miss a dose, take it when you remember unless it's almost time for the next one, then skip and carry on. Don't double up. Thiothixene interacts with other CNS depressants, some antibiotics, and QT-prolonging drugs. The prescriber and pharmacist need a full list of medications and supplements. Alcohol worsens sedation.

Stopping and tapering

Don't stop thiothixene abruptly. A prescriber can step the dose down gradually.

Pregnancy and breastfeeding

Untreated psychosis carries its own risks in pregnancy, and thiothixene passes into breast milk. Anyone who's pregnant, planning a pregnancy, or breastfeeding should talk it through with their prescriber. This isn't medical advice.

Cost and generic availability

Thiothixene has been generic for decades. It's inexpensive and generally covered by insurance without difficulty.

Common questions

Why is thiothixene rarely a first choice today? Atypical antipsychotics generally have gentler movement side effect profiles and lower tardive dyskinesia risk. Thiothixene stays in use mostly where cost matters or where someone has done well on it before.

Is it different from haloperidol? Similar in profile, though from a different chemical family. Effects and side effects overlap heavily.

What movement side effects should I look out for? Stiffness, slow movements, tremor, and restlessness are the common early ones. Acute dystonia (sudden painful muscle spasms) is less common but treatable. Long-term, tardive dyskinesia (involuntary movements, often of the face and mouth) is the main concern.

Do I need blood tests? Yes. Weight, glucose, and lipids at baseline and annually. Movement screening every six months. Prolactin and ECG as clinical situations warrant.

Questions to ask your prescriber

• What are we hoping this treats, and how will we know it's working?
• What movement side effects should I watch for?
• Should we plan for AIMS screening every six months?
• If side effects appear, what would we try next?
• If we decide to stop it later, how would we taper safely?

Sources

This guide draws on current prescribing information and public health references. It is reviewed for clinical accuracy and updated as guidance changes, and current as of June 8, 2026.

• U.S. Food and Drug Administration. Thiothixene prescribing information.
• MedlinePlus, U.S. National Library of Medicine. Thiothixene.
• National Institute of Mental Health. Mental health medications.
• American Psychiatric Association. Practice Guideline for the Treatment of Patients with Schizophrenia, 3rd edition.
• National Institute for Health and Care Excellence (NICE). CG178, Psychosis and schizophrenia in adults.
• Carolan A, et al. Metformin for the Prevention of Antipsychotic-Induced Weight Gain: Guideline Development and Consensus Validation. Schizophrenia Bulletin. 2025;51(5):1193 to 1203.