You're tender everywhere, and nobody knows why. Here's the biological reason.

Your COMT gene produces an enzyme that breaks down catecholamines, a class of brain chemicals that includes dopamine, norepinephrine, and epinephrine. In your pain system, this enzyme is critical for turning off pain signals once they’ve delivered their message. When COMT is working normally, pain signals come in, get processed, and then get cleared away so your brain can move on. Your prefrontal cortex uses dopamine to stay calm and analytical, which also helps suppress pain perception.

The Val158Met variant is carried by roughly 25% of people with European ancestry in homozygous form (slow version). People with the slow COMT variant clear these chemicals much more slowly, meaning pain signals stay active longer and your stress hormones remain elevated. Your brain is flooded with extra dopamine and norepinephrine, which sounds like it should help, but it actually creates a state of constant hyperarousal and amplified threat detection.

You probably notice you’re sensitive to stimulation in general. Loud noises bother you more than they bother others. Bright lights cause discomfort. You feel pain more intensely and recover from it more slowly. You might be a perfectionist or easily overwhelmed by busy environments. Your body stays in a state of heightened alert, and pain signals don’t fade the way they should.

Your body manufactures its own opioids called endorphins and enkephalins. They bind to opioid receptors in your nervous system to suppress pain signals. This is your built-in analgesic system, completely natural and essential for normal pain tolerance. Your OPRM1 gene codes for the mu-opioid receptor, the main receptor that receives these endogenous painkillers.

The A118G variant (G allele), carried by roughly 10 to 15% of people with European ancestry, reduces how effectively your mu-opioid receptor responds to your body’s own endogenous opioids. Even though your body is producing normal amounts of these painkillers, your receptors are less sensitive to them, so your natural pain relief capacity is significantly reduced. It’s like having a dimmer switch instead of a light switch for your pain suppression system.

You likely have a naturally low pain tolerance compared to others. Things that cause mild discomfort for someone else might be quite painful for you. You might have avoided contact sports or physical jobs because pain seems disproportionate to the injury. Rest and time don’t seem to reduce your pain as effectively as they do for others. Your body’s endogenous pain-relief system is working, but it’s not reaching you at full strength.

Your MTHFR gene produces an enzyme that converts folate into its active form, methylfolate, which is essential for a process called methylation. Methylation is your cells’ way of turning genes on and off, making neurotransmitters, and regulating how much nitric oxide your blood vessels produce. Nitric oxide is crucial for blood flow, blood pressure regulation, and pain modulation in your nervous system.

The C677T variant, carried by roughly 40% of people with European ancestry, reduces MTHFR enzyme efficiency by 40 to 70%. Your cells are converting B vitamins into usable forms at a fraction of the rate they should be, which means your methylation cycle is sluggish and your nitric oxide production is impaired. Your blood vessel function suffers, and your nervous system’s pain-suppression mechanisms don’t have the cofactors they need to work properly.

You probably have trouble maintaining stable blood flow, which means your extremities get cold easily and your pain tends to worsen with temperature changes. Your muscles don’t recover as quickly from activity. You might feel exhausted despite sleeping, or experience brain fog that improves slightly when you take the right form of B vitamins. Your pain is often worse during high-stress periods or when you’re not sleeping well, because stress and poor sleep both tax your methylation system.

BDNF stands for brain-derived neurotrophic factor. It’s a protein that allows your brain and nervous system to form new connections, adapt to stress, and recover from injury. In the context of pain, BDNF also modulates central sensitization, the process where your nervous system amplifies pain signals over time. When BDNF is working well, your nervous system can adapt to chronic stress and pain without getting stuck in a heightened state. When it’s not, your nervous system becomes increasingly sensitized.

The Val66Met variant, carried by roughly 30% of the population in the Met-carrying form, is associated with reduced BDNF activity, especially under stress. Your nervous system has a harder time adapting to chronic pain and stress, which means central sensitization tends to develop faster and stronger in you. Your brain’s neuroplasticity, its ability to rewire itself and recover, is compromised. This is especially true if you’ve experienced physical trauma, illness, or prolonged emotional stress.

You probably noticed that after an illness or injury, your pain didn’t resolve the way you expected it to. Instead of improving gradually, it stayed high and sometimes spread to new areas. Stress makes your pain worse more dramatically than it does for others. You might struggle with anxiety or depression alongside your pain, because BDNF also modulates mood resilience. Your body struggles to build new neural pathways away from the pain state.

TRPV1 is a ion channel on the surface of sensory nerve cells that responds to heat, capsaicin (the compound that makes chili peppers spicy), and various inflammatory chemicals. It’s your body’s warning system for dangerous temperatures and chemical threats. Under normal circumstances, TRPV1 has a high activation threshold, so everyday warmth and mild pressure don’t trigger pain. But in some people, TRPV1 variants lower that threshold significantly.

Gain-of-function variants in TRPV1, carried by roughly 25 to 30% of the population, lower the activation threshold for sensory stimuli. Your nerve endings fire pain signals in response to heat, pressure, and chemical signals that wouldn’t normally cause pain in other people. It’s like your warning system is set to alarm at a lower temperature and lower pressure than the factory setting. You’re literally more sensitive to your environment at the cellular level.

You probably notice that warm showers or baths feel uncomfortably hot, even at temperatures others find pleasant. Spicy foods cause excessive burning. Tight clothing causes localized pain or burning sensations. Pressure on your skin, like firm massage or even tight hugs, feels like pain rather than relief. Your body perceives normal tactile input as a threat that requires a pain signal. Weather changes, especially warming, can trigger widespread discomfort.

Your GCH1 gene produces an enzyme called GTP cyclohydrolase 1, which manufactures tetrahydrobiopterin (BH4). BH4 is a cofactor, meaning it’s a helper molecule that enables other crucial processes. In your nervous system, BH4 is essential for producing several key neurotransmitters that suppress pain and regulate mood, including serotonin and dopamine. Without sufficient BH4, your nervous system can’t make adequate amounts of these pain-suppressing chemicals, even if you have normal levels of the precursor amino acids.

Variants in GCH1 that reduce BH4 production are carried by roughly 15 to 20% of the population. Your body can’t produce adequate BH4, which means your pain-modulating neurotransmitters are undersupplied at the factory level, leaving you with chronically reduced pain suppression. This is independent of whether you’re eating enough protein or taking B vitamins. Your cells simply can’t manufacture the BH4 they need to make these chemicals in normal amounts.

You probably have pain that responds poorly to standard interventions because the problem isn’t that you lack precursor nutrients, it’s that your body can’t assemble them into the finished neurotransmitters. Your pain might have a quality of burnout or exhaustion to it, because serotonin depletion makes pain feel more intense and recovery feel more difficult. Mood disturbances often accompany your pain, and they tend to fluctuate together.