Feeling cold and shaky at the same time usually means your body is trying to generate heat, regulate blood sugar, or respond to a perceived threat. The combination points to a short list of common causes, most of them harmless and fixable within minutes. In some cases, though, it signals something that needs medical attention.
Your Body’s Shivering Reflex
Shivering is an involuntary muscle contraction your body uses to produce heat. It’s controlled by a thermoregulatory center deep in your brain that acts like a thermostat. When your skin senses cold, or when infection triggers fever-related chemicals, this brain region sends signals down through your spinal cord to your skeletal muscles, telling them to contract rapidly. That rapid contraction is what you feel as shaking.
This means coldness and shakiness aren’t two separate problems. They’re often two parts of a single response: your body detected a temperature drop (real or internally manufactured) and activated the same heat-generating mechanism.
Low Blood Sugar
If you haven’t eaten in a while, or you ate something sugary and crashed afterward, low blood sugar is one of the most common explanations for suddenly feeling cold and shaky. Blood sugar below 70 mg/dL is considered low, and below 54 mg/dL is severe. Your body responds to dropping blood sugar by releasing stress hormones, which cause a fast heartbeat, sweating, shakiness, irritability, dizziness, and hunger.
The fix is straightforward: eat or drink something with fast-acting carbohydrates, like juice, glucose tablets, or a few pieces of candy, then follow up with a more balanced meal. Most people feel better within 15 to 20 minutes. If you notice this pattern regularly and you don’t have diabetes, it’s worth paying attention to how long you go between meals and whether your meals include enough protein and fat to slow the release of sugar into your bloodstream.
Fever and Infection
Feeling freezing cold while your temperature is actually rising is a hallmark of fever. During an infection, immune signals reach your brain’s thermostat and essentially reset it to a higher target temperature. Your brain now “thinks” your normal body temperature is too low, so it triggers shivering to generate heat and constricts blood vessels in your skin to conserve it. You feel genuinely cold, pile on blankets, and shake, all while your core temperature climbs above the normal range of 97°F to 99°F.
These intense shaking episodes during fever are called rigors. They can be dramatic, with full-body trembling and teeth chattering, and they typically happen as the fever is spiking. Once your temperature reaches the new set point, the shivering usually stops and you may start feeling hot instead. A temperature over 100.4°F generally confirms a fever caused by infection or illness.
Most fevers from common viruses resolve on their own. But if you also have a stiff neck, rapid heartbeat, shallow breathing, confusion, or a spreading skin rash, those are signs of a potentially serious infection like sepsis that needs urgent medical care.
Anxiety and the Stress Response
Anxiety can make you feel cold and shaky without any change in your environment or health. When your brain perceives a threat, whether it’s a looming deadline or a full-blown panic attack, your sympathetic nervous system floods your body with stress hormones. These hormones tighten the blood vessels in your skin (making your hands and feet feel icy), tense your muscles, and spike your blood sugar for quick energy. The resulting fluctuations in blood sugar can leave you feeling shaky and nauseous, even if you’ve eaten recently.
People experiencing anxiety-driven shakiness often describe it as an internal trembling that’s hard to control. It can come on suddenly and feel alarming, which only feeds the anxiety cycle. If this happens to you, slow breathing (inhaling for four counts, exhaling for six to eight) helps shift your nervous system out of fight-or-flight mode. The cold, shaky feeling typically fades within 20 to 30 minutes as stress hormones clear.
Cold Exposure and Hypothermia
If you’ve been outside in cold weather or in a cold building for an extended time, the explanation may be simple: your body is losing heat faster than it can produce it. Mild hypothermia begins when your core temperature drops below 95°F, and early symptoms include hunger, nausea, fatigue, shivering, and pale skin.
Your body shivers vigorously during mild hypothermia because that’s its primary defense. But if your core temperature continues dropping to around 86°F to 90°F, shivering actually stops. This is a dangerous sign, not a sign of improvement. It means your body’s energy reserves are depleted and your muscles can no longer sustain the contractions. Cognitive decline and confusion set in at this stage. If someone who was shivering in the cold suddenly stops and seems drowsy or confused, they need emergency warming.
Iron Deficiency and Anemia
Chronic coldness paired with shakiness, fatigue, and pale skin can point to iron-deficiency anemia. When you don’t have enough iron, your blood carries less oxygen from your lungs to your tissues. This reduced oxygen availability directly impairs two things your body relies on to stay warm: the ability to constrict blood vessels in your skin (which conserves heat) and the ability to ramp up your metabolic rate (which generates heat).
Research from the National Academies of Sciences shows that iron-deficient people also have lower thyroid hormone levels and exaggerated stress hormone responses to cold, compounding the problem. The good news is that restoring iron levels with supplements measurably improves the body’s ability to maintain temperature in cold environments. If you’re consistently colder than the people around you and also dealing with fatigue or shortness of breath, a simple blood test can check your iron and hemoglobin levels.
Underactive Thyroid
Your thyroid gland sets the pace of your metabolism. When it underperforms, a condition called hypothyroidism, your basal metabolic rate drops. That means your body produces less heat at rest, which is why increased cold sensitivity is one of the most commonly reported symptoms. Even moderate hypothyroidism reduces the body’s ability to generate heat in response to cold environments.
Studies have confirmed that restoring normal thyroid hormone levels significantly improves this cold-induced heat generation. Hypothyroidism also causes fatigue, weight gain, dry skin, and sluggish thinking. It develops gradually, so many people adapt to feeling cold and tired without realizing it’s abnormal. A blood test measuring thyroid-stimulating hormone is the standard way to check.
Caffeine and Medication Effects
Too much caffeine is an underappreciated cause of shakiness. The FDA considers up to 400 milligrams per day safe for most adults, roughly four standard cups of coffee. Go beyond that and you can feel jittery, agitated, and shaky, sometimes with cold sweats as your body tries to manage the stimulant overload.
Several common medications can also cause tremors. Antidepressants (including SSRIs), asthma inhalers, lithium, certain seizure medications, stimulants like amphetamines, and even too much thyroid medication can all trigger shaking. If you recently started a new medication or changed your dose and noticed shakiness, that timing is worth noting. Nicotine and alcohol withdrawal can produce similar tremors paired with cold sweats.
Sorting Out the Cause
The fastest way to narrow it down is to consider the context. If it came on suddenly and you haven’t eaten in hours, try eating something and see if it resolves. If you’ve been in a cold environment, get warm. If you’re also feeling feverish, achy, or congested, you’re likely fighting an infection. If it happens during moments of stress or worry, anxiety is the most probable trigger.
Patterns matter more than single episodes. Feeling cold and shaky once after skipping lunch is unremarkable. Feeling cold and shaky repeatedly, especially if it comes with fatigue, weight changes, or dizziness, suggests something systemic like anemia or a thyroid issue that a blood test can identify. And if the shaking is accompanied by confusion, a very high or very low temperature, rapid heartbeat, or difficulty breathing, that’s a situation that warrants immediate medical attention.