Feeling cold is a real side effect of a surprising range of drugs, from heart pills and psychiatric medicines to alcohol and some cancer treatments. They don’t all do it the same way, because feeling cold and actually being cold are different things. Some drugs only change how warm your hands feel or how your nerves sense cold, while a few can lower the temperature of your whole body.
How Your Body Keeps Itself Warm
A small area at the base of the brain, the hypothalamus, works like a thermostat. It reads temperature signals from the body and adjusts heat-making and heat-saving responses to keep core temperature within about 1°C.1PubMed Central. Drug-Induced Hyperthermia Review A fever works by turning this thermostat up, which is why you shiver with chills while you are not actually cold. Some drugs can nudge the setting down or up, so the body aims for a cooler or warmer temperature.2The Journal of Pharmacology and Experimental Therapeutics. Behavioral thermoregulatory responses to selective mu, delta and kappa opioid agonists in rats
Shivering and goosebumps are the brain’s response to a gap between its target temperature and the temperature it senses. A drug that shifts the brain’s target can therefore trigger chills while a thermometer reads normal.
The body has three main tools to stay warm. To save heat, blood vessels in the skin, hands, and feet narrow so less warm blood reaches the surface. To make heat, muscles shiver and burn sugar for energy. Thyroid hormone sets how fast the body burns fuel, which affects how much heat it produces all day. A drug can make you cold by narrowing vessels too much, blocking shivering, slowing metabolism, or confusing the nerves that sense cold.
The distinction that matters most is between feeling cold and being cold. Cold hands or feet with a normal thermometer reading usually point to a blood-flow or nerve effect. A low reading means the whole body has cooled, which is more serious.
Antipsychotics and Other Psychiatric Medicines
Antipsychotic medicines can cause hypothermia, a drop in core body temperature that can become dangerous.3PubMed Central. Hypothermia due to Antipsychotic Medication: A Systematic Review The brain’s dopamine and serotonin signals help hold temperature steady, and these drugs block some of them.4PubMed Central. Hypothermia due to Antipsychotic Medication: A Systematic Review Blocking one particular serotonin signal is thought to be the main reason many newer antipsychotics, including clozapine, can lower temperature.5PubMed Central. A case report of acute hypothermia during initial inpatient clozapine titration with review of current literature on clozapine-induced temperature dysregulations
In one reported case, a 67-year-old woman’s temperature fell to 27.8°C within 8 hours of her first 10 mg dose of olanzapine, with no cold exposure.6Eurasian Journal of Emergency Medicine. Hypothermia as a Medication Side Effect Such drops are uncommon, and most people on antipsychotics never develop dangerous cooling. The risk seems highest when the drug is first started or the dose is raised.
Early on, a person may feel unusually chilly, tired, or slowed down, which is easy to mistake for ordinary sedation from the medicine. Because those signs are vague, a thermometer is the only way to tell mild sedation from a cooling body. A reading a degree or so under normal with no other symptoms is a reason to call the prescriber that day, not a reason to panic.
Some signs point to a real drop. Shivering that stops while the person still feels cold is a bad sign. So are confusion, slurred speech, unusual sleepiness, and a slow pulse. A reading below 35°C (95°F) needs emergency care. Caregivers should watch most closely in the first days after a start or a dose increase.
Stopping an antipsychotic suddenly can bring back symptoms or cause withdrawal, so don’t stop it on your own. Mild chilliness is worth mentioning at the next appointment, since the prescriber can lower the dose or switch to a different drug.
Beta Blockers and Cold Hands and Feet
Beta blockers can narrow small blood vessels and reduce blood flow to the hands and feet.7News-Medical. Beta Blocker Side Effects Fingers and toes can then feel cold even though core temperature stays normal. Beta blockers differ in how much they do this, and the difference doesn’t follow the usual way the drugs are grouped.8PubMed Central. Peripheral vasoconstriction induced by β-adrenoceptor blockers: a systematic review and a network meta-analysis Switching to a different one may help if cold hands bother you.
On a beta blocker, hands and feet may feel cold, look pale, or turn slightly blue, especially outdoors or in air conditioning. It often starts soon after beginning the drug or raising the dose. Numbness that comes with sharp color changes or sores should be checked by a doctor.
Raynaud’s causes sharp, episodic color changes, typically white then blue then red, triggered by cold or stress. A beta blocker can make an existing tendency to these attacks worse, so a history of them is worth telling the prescriber before or after starting the drug.
Gloves, warm socks, and layers help more than raising the room heat. Moving and stretching your fingers and toes increases blood flow. Never stop a beta blocker abruptly, because heart rate and blood pressure can rebound.
Beta blockers protect the heart, so cold hands are weighed against benefits like controlling heart rhythm, lowering blood pressure, or protecting the heart after a heart attack. That is why the usual first move is adjusting or switching the drug.
Thyroid Medicines That Slow Your Metabolism
Methimazole, used for an overactive thyroid, can push thyroid hormone too low, causing hypothyroidism, an underactive thyroid.9Mayo Clinic. Methimazole (oral route) – Side effects & dosage Feeling cold is one sign, along with tiredness, constipation, dry skin, weight gain, and a slow heartbeat.10Mayo Clinic. Methimazole (oral route) – Side effects & dosage Contact your doctor if these appear, since a blood test can check your hormone level.11Mayo Clinic. Methimazole (oral route) – Side effects & dosage
This cold differs from other drug causes. It builds slowly over weeks rather than hours, and the whole body feels cold, not just the hands and feet. It usually comes with other slowing symptoms like tiredness and weight gain.
The blood test measures thyroid-stimulating hormone, which the brain raises when thyroid hormone runs low, so a high value points to an underactive thyroid. A low hormone level confirms the drug is overshooting, while a normal result suggests the cold has another cause. People on these drugs usually get repeat tests, so a chilly spell can be timed to a check-up that is already due.
A dose change usually fixes the problem once the test confirms the cause. Thyroid hormone acts slowly, so after the dose is lowered it can take weeks before warmth and energy come back. Feeling no better after a few days doesn’t mean the adjustment failed, but persistent symptoms should be reported at the follow-up test.
Alcohol and Cannabis
Alcohol widens blood vessels in the skin, giving a warm flush while heat escapes faster.12Mountain Med Consulting. How does alcohol make us more susceptible to hypothermia? The body is cooling while you feel warmer, and the sensation of warmth can stop you from putting on a coat.
In the cold, the bigger problem is that alcohol lowers blood sugar, which weakens shivering, the body’s main way to make heat.13Journal of Wilderness Medicine. Alcohol ingestion and temperature regulation during cold exposure Shivering burns sugar, and alcohol interferes with the liver’s ability to release stored sugar. Drinking on an empty stomach makes this worse, because there are fewer reserves to start with. Alcohol also dulls judgment, so intoxicated people may not notice they are cold or seek shelter. Drinking outdoors in cold weather therefore raises the risk of a dangerous drop in body temperature.
Don’t rely on a drink to warm you up outdoors. Eating before and during drinking supports blood sugar and shivering. Never let an intoxicated person sleep outside or in an unheated space.
An intoxicated person asleep in a cool room can lose heat over hours. A person who is cold to the touch, hard to rouse, or breathing slowly after drinking needs medical help, not sleep.
THC, the active part of cannabis, acts on signals in the hypothalamus that help control temperature.14Plenny. Why Does Weed Make You Feel Cold or Give You Chills? Some people feel chilly or shiver after using it, which usually passes as the effect wears off.
Chemotherapy and Cold Sensitivity
Oxaliplatin, a chemotherapy drug commonly used for bowel cancer, often damages sensory nerves.15IBRO Neuroscience Reports. OXALIPLATIN INDUCES COLD AND MECHANICAL ALLODYNIA IN A SEX-DEPENDENT MANNER AND ALTERS MECHANOSENSITIVITY OF MOUSE SOMATOSENSORY NEURONS Touching cool things can then cause tingling or pain.16PubMed Central. Pathological Mechanisms and Preventive Strategies of Oxaliplatin-Induced Peripheral Neuropathy The drug changes the nerves that detect cold, making them fire far too easily.17PubMed Central. Oxaliplatin-induced cold hypersensitivity is due to remodelling of ion channel expression in nociceptors In animals, the sensitivity peaked a few days after a dose and then faded.18PubMed Central. Oxaliplatin-induced cold hypersensitivity is due to remodelling of ion channel expression in nociceptors Symptoms often flare in the days after each treatment and ease before the next.
Your body temperature is normal, so warming the room does little; contact with cold sets off the symptoms. It’s also not an allergic reaction, so antihistamines won’t help.
Day to day, cold drinks can cause throat tightness or tingling. Opening the fridge or touching cold metal can sting the fingers, and cold air on the face can bring discomfort around the mouth.
Breathing in cold air can cause throat tightness or a feeling of difficulty swallowing, which can be frightening. This is a nerve effect and not a true blockage of the airway, though anyone with real breathing trouble should seek help right away. Covering the mouth and nose with a scarf warms the air before it’s inhaled.
In the days after treatment, drink room-temperature or warm drinks. Wear gloves to handle frozen food and to go outside. Tell your cancer team if symptoms last between cycles, since lasting nerve damage can affect dosing.
Opioids and Withdrawal Chills
Morphine-type opioids generally push the body toward holding heat.19PubMed. The opioid system and temperature regulation But when someone stops after long-term use, withdrawal often makes cold feel painful.20PubMed. Opiates modulate thermosensation by internalizing cold receptor TRPM8 Chills and goosebumps during tapering are a common, expected part of withdrawal.
During withdrawal the body’s temperature control swings, so people can alternate between chills and sweating. Goosebumps and cold sensitivity occur together with other signs such as muscle aches and restlessness, so cold alone isn’t the whole picture.
Taper under a doctor’s guidance rather than stopping suddenly. Warm layers and blankets ease chills, and it’s worth asking about medicines that ease withdrawal symptoms. Painful cold sensitivity can make quitting harder, so mention it early.
Withdrawal chills don’t usually mean the core temperature has fallen dangerously. Someone who feels extremely cold with confusion or drowsiness still needs a thermometer and medical attention. Chills that come with fever, vomiting, or severe symptoms need to be checked rather than assumed to be withdrawal.
Who Is Most at Risk of a Dangerous Drop
Being older raises the risk of a drug-related drop in body temperature.21OBM Geriatrics. Olanzapine-Induced Hypothermia: A Case Report in an Elderly Black Male Patient Diagnosed with Bipolar 1 Type Disorder An underactive thyroid, diabetes, kidney or liver failure, serious infection, or a past stroke add risk.22OBM Geriatrics. Olanzapine-Induced Hypothermia: A Case Report in an Elderly Black Male Patient Diagnosed with Bipolar 1 Type Disorder So does drinking alcohol or taking sedatives like benzodiazepines on top of an antipsychotic.23OBM Geriatrics. Olanzapine-Induced Hypothermia: A Case Report in an Elderly Black Male Patient Diagnosed with Bipolar 1 Type Disorder Low muscle mass and moving less mean the body makes less heat, which affects the very old and very young most.24OBM Geriatrics. Olanzapine-Induced Hypothermia: A Case Report in an Elderly Black Male Patient Diagnosed with Bipolar 1 Type Disorder General anesthesia lowers the point at which shivering starts by 2–3°C, one reason people are kept warm during surgery.25PubMed Central. Temperature management under general anesthesia: Compulsion or option
Older adults often sense cold less sharply, so they may not feel chilled until their temperature has already dropped. Their skin vessels also narrow less effectively, so they hold heat less well when drugs add to the problem.
An older person on an antipsychotic who also drinks and has an underactive thyroid faces far more than any one factor suggests. Reviewing the full medicine list when a new drug is added helps spot combinations that raise the chance of cooling. A new sedative added to an existing drug is the kind of change worth asking the pharmacist about.
Anemia, low body weight, and poor circulation also cause feeling cold, and infections can cause chills before a fever rises. If coldness started before the drug, the medicine is less likely to be the cause.
New coldness after a new drug is worth a call to your pharmacist or doctor, and bringing a list of all medicines, including alcohol and cannabis use, helps. Families of older relatives on antipsychotics should keep a thermometer at home.