I've been experiencing hypothermia and changes in habits and behavior after starting Invega Sustenna (paliperidone), what could be the cause?

Hypothermia and Behavioral Changes After Invega Sustenna

Invega Sustenna (paliperidone palmitate) can cause hypothermia as a rare but serious adverse effect, and you should immediately contact your prescribing physician to report these symptoms, as this may require medication discontinuation or dose adjustment. 1

Understanding Your Symptoms

Hypothermia from Paliperidone

• Hypothermia (feeling abnormally cold) is a documented adverse effect of paliperidone, the active ingredient in Invega Sustenna, though it occurs rarely 1
• This side effect can occur at any time during treatment—not just in the first few days or weeks—and has been reported even after years of stable treatment 1
• The mechanism involves dopamine D2 receptor blockade affecting the hypothalamus, which regulates body temperature 2

Behavioral and Habit Changes

Behavioral changes with antipsychotics like paliperidone can represent several distinct conditions that require different management:

1. Simple Medication Side Effects

• Cognitive and behavioral changes including altered habits, anxiety, and mood changes are recognized adverse effects of antipsychotic medications 3
• These typically develop gradually and are not accompanied by severe physical symptoms 4

2. Neuroleptic Malignant Syndrome (NMS) - Medical Emergency

You must be evaluated urgently if you have ANY of the following in addition to feeling cold:

• Muscle rigidity or stiffness (especially "lead pipe" rigidity where limbs resist movement) 2, 5
• High fever (temperature above 100.4°F/38°C) 2, 5
• Confusion or altered mental status 2, 5
• Rapid heart rate, high blood pressure, or profuse sweating 2, 5
• Tremors or involuntary muscle movements 5

NMS is a life-threatening condition that can occur with long-acting injectable antipsychotics like Invega Sustenna, even after the first injection 5. Mortality has decreased from 76% to less than 10-15% with prompt recognition and treatment 2.

Critical Distinction: Hypothermia vs. Hyperthermia

Important caveat: While you report feeling cold (suggesting hypothermia), NMS causes hyperthermia (high fever). These are opposite conditions:

• Hypothermia (low body temperature, feeling cold): Rare paliperidone side effect requiring medication review 1
• Hyperthermia (high fever): Component of NMS requiring emergency treatment 2, 5

Check your actual body temperature with a thermometer immediately to determine which condition you may have.

Immediate Actions Required

If Your Temperature is Below 95°F (35°C):

• Contact your prescribing psychiatrist immediately 1
• The hypothermia is likely medication-related and typically reverses with drug withdrawal 1
• Do not stop Invega Sustenna abruptly without medical supervision, as it is a long-acting injection that will remain in your system

If Your Temperature is Above 100.4°F (38°C) OR You Have Muscle Rigidity:

• Go to the emergency department immediately 2, 5
• This could represent NMS, which requires urgent discontinuation of the medication and intensive supportive care 2
• Treatment includes benzodiazepines, external cooling measures, IV fluids, and potentially bromocriptine 5

If Your Temperature is Normal (95-100.4°F):

• Still contact your psychiatrist within 24-48 hours to report behavioral changes 4
• The sensation of feeling cold without actual hypothermia may represent altered temperature perception, which can occur with antipsychotics
• Behavioral changes alone warrant medication review but are not typically emergent 3

Special Considerations for Long-Acting Injectable Paliperidone

Invega Sustenna presents unique challenges compared to oral medications:

• The medication releases over 4 weeks to 4 months after injection, with peak levels at 13 days 6, 7
• Adverse effects may have delayed onset and can appear days after injection 5, 8
• Symptoms persist longer than with oral medications because the drug cannot be immediately cleared from your system 6
• If medication discontinuation is needed, supportive treatment must continue until the drug is metabolized, which can take weeks 6

Common Pitfall to Avoid

Do not assume feeling cold is simply environmental or unrelated to your medication. Hypothermia from paliperidone is under-recognized because it is rare, but it is a documented, potentially serious adverse effect that requires medical evaluation 1. The long-acting nature of Invega Sustenna means that even if you've tolerated previous injections well, new adverse effects can still emerge 1.