What meds can cause low body temperature?: An overview of drug-induced hypothermia

Certain drug classes can significantly disrupt the body's thermoregulation, leading to a drop in core body temperature, a condition known as hypothermia. While often associated with cold exposure, this potentially serious side effect can be caused by various medications. Knowing what meds can cause low body temperature is crucial for patients and healthcare providers alike to ensure proper monitoring and management.

Quick Summary

This article explores the various medications and drug classes that can lead to hypothermia by disrupting the body's temperature-regulating mechanisms. These include antipsychotics, beta-blockers, sedatives, and alcohol. Key risk factors and prevention strategies are also discussed.

Key Points

• Antipsychotics: Both typical and atypical antipsychotic drugs, such as olanzapine and risperidone, can disrupt the brain's temperature control center and cause hypothermia.

• Beta-Blockers: Medications like propranolol, used for heart conditions, can cause low body temperature by decreasing blood flow to the skin and affecting heat regulation.

• Sedatives and Anesthetics: Drugs that depress the central nervous system, including general anesthetics, benzodiazepines, and opioids, can impair shivering and cause vasodilation, leading to heat loss.

• Metformin Overdose: In large overdoses, the diabetes medication metformin can lead to severe hypoglycemia and subsequently cause a dangerous drop in body temperature.

• Alcohol Consumption: In cold environments, alcohol causes peripheral vasodilation and impairs shivering, leading to rapid heat loss and increased risk of hypothermia.

• Risk Factors: The elderly, those with other medical conditions like hypothyroidism or diabetes, and patients on multiple CNS-acting drugs are at higher risk for drug-induced hypothermia.

• Management: In cases of suspected drug-induced hypothermia, rewarming and consulting a healthcare professional to potentially adjust or discontinue the medication are critical steps.

How Medications Affect Body Temperature

Thermoregulation is a complex process controlled by the hypothalamus, a region in the brain responsible for maintaining the body's core temperature. Medications can interfere with this system in several ways, including by affecting neurotransmitters, altering blood flow, and depressing central nervous system function. This can lead to the body losing heat faster than it can produce it, resulting in a low body temperature.

Antipsychotics and Hypothermia

Antipsychotic drugs (APDs), both typical and atypical, are well-known for their potential to disrupt thermoregulation and cause hypothermia. Some APDs were even initially used to induce "artificial hibernation" by lowering body temperature in anesthesia.

Mechanisms of Action

• Dopamine and Serotonin Blockade: Many antipsychotics act by blocking dopamine and serotonin receptors in the brain, particularly in the hypothalamus. Disrupting these signals can impair the body's internal thermostat. Second-generation antipsychotics, which act on both dopamine (D2) and serotonin (5-HT2) receptors, are frequently associated with hypothermia.
• Alpha-adrenergic Receptor Antagonism: Some APDs, such as chlorpromazine, risperidone, and clozapine, also act as alpha-adrenergic receptor antagonists, which can contribute to hypothermia.

Common Antipsychotics Implicated

Case reports and database analyses have linked numerous antipsychotics to hypothermia. Some of the most frequently cited include:

• Olanzapine (Zyprexa): Several cases and database reports show a link between olanzapine use and hypothermia, especially during initiation or dose changes.
• Risperidone (Risperdal): In one database review, risperidone was responsible for 27% of all reported cases of antipsychotic-related hypothermia.
• Haloperidol (Haldol): This typical antipsychotic has been associated with hypothermia, particularly at higher doses.
• Quetiapine (Seroquel): This medication has also been documented to cause hypothermia.

Cardiovascular Medications

Certain medications used to treat heart conditions and high blood pressure can also interfere with the body's ability to maintain a stable temperature.

Beta-Blockers

Beta-blockers like propranolol are known to cause a drop in body temperature by impeding the body's ability to generate and conserve heat. They work by blocking beta-adrenergic receptors, which in turn reduces the body's ability to increase blood flow to the skin, a key mechanism for heat dissipation. This can make it harder for the body to cool down in the heat, but also impairs thermoregulatory vasoconstriction, which is needed to conserve heat in cold conditions.

Alcohol and Low Body Temperature

While not a prescription drug, alcohol is a substance that significantly impairs thermoregulation, often leading to a drop in core body temperature.

• Peripheral Vasodilation: Alcohol causes blood vessels near the skin's surface to dilate, creating a false sensation of warmth. This vasodilation, however, causes the body to lose heat rapidly to the environment.
• Impaired Shivering: In cold conditions, alcohol also impairs shivering, a crucial mechanism for generating heat.
• Impaired Cognition: The cognitive impairment from alcohol can also prevent a person from seeking warmer shelter, further increasing the risk of hypothermia.

Sedatives, Anesthetics, and Opioids

Medications that depress the central nervous system, including sedatives, anesthetics, and opioids, can cause low body temperature by interfering with the hypothalamus.

Mechanisms of Action

• CNS Depression: These drugs reduce metabolic heat production and impair the body's autonomic responses to cold, such as shivering and vasoconstriction.
• Vasodilation: General anesthetics, propofol, and opioids like morphine and meperidine cause vasodilation, leading to core-to-peripheral heat redistribution and rapid heat loss.

Examples of Implicated Drugs

• General Anesthetics: Volatile anesthetics and propofol are known to cause significant heat loss during surgery.
• Opioids: Morphine and meperidine can impair hypothalamic function and depress sympathetic outflow.
• Benzodiazepines: High-dose midazolam has been shown to impair thermoregulatory vasoconstriction, leading to core temperature drops.

Other Medications

Other drug classes can also contribute to the risk of developing hypothermia, often in specific contexts.

• Metformin: While not typically associated with hypothermia at standard doses, massive overdoses of the diabetes medication metformin have been linked to severe hypoglycemia and hypothermia.
• Antidepressants: While most research focuses on heat intolerance, some antidepressants like tricyclic antidepressants (TCAs) have been shown to affect thermoregulation. In certain cases, long-term use has been associated with changes in temperature regulation.
• Anticonvulsants: Medications like valproic acid and oxcarbazepine have been associated with hypothermia in some case reports, especially in elderly patients.

Preventing and Managing Drug-Induced Hypothermia

Prevention is the most effective strategy, especially for vulnerable individuals. Clinicians should be aware of the medications that affect thermoregulation, and patients should be educated on the potential side effects and risk factors.

Monitoring and Risk Factors

• Age: Older adults are at increased risk due to lower baseline temperatures and changes in metabolism and fat distribution.
• Comorbidities: Conditions like diabetes, hypothyroidism, and sepsis can also increase the risk.
• Environmental Factors: Exposure to cold environments is a major risk factor for patients taking these medications.
• Monitoring: For patients initiating or changing the dose of a high-risk medication, careful monitoring of body temperature is recommended.

What to Do if Symptoms Occur

If drug-induced hypothermia is suspected, it is vital to seek medical attention. The management approach typically involves:

• Rewarming: Using blankets, warm liquids, or forced-air systems to increase core body temperature.
• Discontinuation or Dosage Adjustment: The offending medication may need to be discontinued or its dose adjusted under medical supervision.
• Addressing the Underlying Condition: Ensuring the primary condition being treated is managed appropriately.

Medication Comparison Table

Drug Class	Examples	Mechanism of Action	Special Considerations
Antipsychotics	Olanzapine, Haloperidol, Risperidone	Dopamine and serotonin antagonism in the hypothalamus impairs thermoregulation; can cause vasodilation.	Risk increases at initiation or dose change, especially in older adults.
Beta-Blockers	Propranolol	Reduces blood flow to the skin, interfering with the body's ability to regulate temperature via vasodilation.	Blunts the effects of the body's natural response to cold.
Sedatives/Hypnotics	Benzodiazepines (Midazolam), Phenothiazines	Depress the central nervous system and inhibit thermoregulatory responses like shivering and vasoconstriction.	Dose-dependent effect; can worsen with alcohol use.
Opioids	Morphine, Meperidine, Fentanyl	Impair hypothalamic thermoregulation and depress overall sympathetic outflow.	Potent CNS depressants that reduce the body's ability to respond to temperature changes.
Alcohol	Ethanol	Causes vasodilation, leading to rapid heat loss from the skin, and impairs shivering.	Also impairs cognition, preventing behavioral responses to cold.
Anticonvulsants	Valproic Acid, Oxcarbazepine	Can interfere with neurotransmitter systems involved in temperature regulation.	Reports are generally less frequent and often involve combinations of medications or elderly patients.
Antidepressants	Tricyclics (Amitriptyline)	Certain types have anticholinergic effects that may impact temperature regulation.	Less common cause of hypothermia than other classes; effects can vary.

Conclusion

Drug-induced hypothermia is a potentially dangerous side effect, and awareness is key to its prevention and management. Medications that can cause low body temperature often act on the central nervous system or cardiovascular system, interfering with the body's natural thermoregulation. Antipsychotics, beta-blockers, sedatives, opioids, and alcohol are among the most common culprits. Risk is increased in older adults, those with underlying medical conditions, and during dose changes or initiation of therapy. Recognizing the signs of hypothermia and promptly seeking medical help is crucial for a positive outcome. If you are concerned about your medication, it is important to discuss it with your healthcare provider rather than stopping it on your own.

For more information on heat-related illnesses and medications that can affect temperature, consult the Centers for Disease Control and Prevention's guidance on Heat and Medications.

Frequently Asked Questions

Can common antidepressants cause a drop in body temperature?

While less common than with antipsychotics, some antidepressants, particularly tricyclic antidepressants, can affect thermoregulation due to anticholinergic effects. However, some selective serotonin reuptake inhibitors (SSRIs) and serotonin-norepinephrine reuptake inhibitors (SNRIs) can cause increased sweating, which can also contribute to a drop in core body temperature.

Why do sedatives and anesthetics cause hypothermia?

Sedatives and anesthetics depress the central nervous system, including the hypothalamus which controls body temperature. They can also cause vasodilation, a widening of blood vessels, which redistributes heat from the core to the periphery and increases heat loss from the skin.

Are older adults at a higher risk for drug-induced hypothermia?

Yes, older adults are at a higher risk. They may have a lower baseline body temperature, a slower metabolism that produces less heat, and often take multiple medications that affect temperature regulation.

What are the warning signs of medication-induced hypothermia?

Symptoms can range from mild to severe and include feeling cold or shivery, cognitive decline, confusion, lethargy, and a low reading on a thermometer. In severe cases, symptoms can progress to paradoxical undressing, unresponsiveness, and arrhythmias.

Can cold exposure worsen the effects of these medications?

Yes. Patients taking medications that affect thermoregulation are at a much higher risk of developing hypothermia in cold environments, as their body's ability to compensate for the cold is impaired.

Does alcohol significantly increase the risk of hypothermia with medication?

Yes, alcohol can exacerbate the effects of other drugs, especially central nervous system depressants like sedatives and opioids. It causes rapid heat loss through vasodilation and impairs shivering, compounding the effects of the medication.

Is drug-induced hypothermia a common side effect?

Severe drug-induced hypothermia is relatively rare, but mild drops in body temperature may be more common, especially with certain drug classes like antipsychotics and in vulnerable populations. Regular monitoring is essential, particularly during the initiation or adjustment of therapy.

Can metformin cause low body temperature in non-overdose cases?

In standard, therapeutic doses, metformin is not a typical cause of hypothermia. The risk is primarily associated with massive overdoses, which lead to severe hypoglycemia and lactic acidosis, contributing to hypothermia.