Individual Responses to Medication – Why Don’t Antidepressants Work the Same for Everyone?
Patients often face an apparent paradox: an antidepressant that increases serotonin levels may calm one person and help them sleep, but in another, it may provoke anxiety, agitation, or a sudden surge of energy. While the explanation lies in brain neurochemistry, it can be conveyed in a simple, understandable way — which is essential for truly grasping how treatment works.
Mood, energy levels, and the intensity of anxiety symptoms depend on a complex chemical balance in the brain. Serotonin, noradrenaline, and dopamine aren’t “happiness hormones” — they act differently depending on which receptors they activate. For example, serotonin has a calming effect when it stimulates 5-HT1A receptors, but may increase anxiety or arousal when acting on 5-HT2A or 5-HT2C receptors.
That’s why two drugs (or sometimes even the same one), which formally increase serotonin levels, can act differently — it all depends on their receptor profile. Take trazodone: in low doses, it helps with sleep and anxiety; in higher doses, it works as an activating antidepressant.
The Role of Individual Patient Differences
That’s only part of the story. The same medication can produce completely different results in two people. Why? First, each person has unique receptor sensitivity and neurochemistry. One patient may feel immediate relaxation, while another experiences restlessness or even irritability.
Second, genetic differences in how medications are metabolized play a major role. Enzymes such as CYP2D6 and CYP2C19, part of the cytochrome P450 family, break down drugs in the liver. Some people metabolize medications too slowly — leading to side effects — while others break them down too quickly, diminishing their therapeutic effect. Pharmacogenetic testing can help predict such outcomes.
Another key factor is a patient’s overall psychophysiological state. Chronic stress, disrupted sleep, lack of emotional support, or bodily tension can reduce the effectiveness of even the best-suited medication. Psychopharmacology doesn’t work in isolation — it unfolds within the context of real life.
The time of day a medication is taken can also make a difference. Some drugs are activating and work better in the morning, while others — such as trazodone or mirtazapine — are best taken in the evening due to their sedative properties. Other substances, including alcohol, supplements, or herbal remedies (like St. John’s wort), can also affect how antidepressants are metabolized and how well they work. Always inform your doctor about everything you’re taking.
Treatment Is a Collaborative Process
Choosing the right antidepressant is not about randomly picking a pill — it’s a process that requires knowledge, precision, and cooperation between doctor and patient. One person might benefit most from an activating medication, another from something stabilizing and calming. In some cases, a combination may be best.
Importantly, antidepressants don’t work instantly. The body needs time to adjust — usually 2 to 6 weeks. In the early days, symptoms may even temporarily worsen. That can be tough, but it’s worth getting through. Treatment isn’t about numbing emotions — it’s about restoring balance and helping you return to life, with greater self-awareness.
If you’ve noticed that something is changing inside — your emotions feel heavier, your motivation has disappeared, your sleep is falling apart — give yourself permission to talk to someone. At the Plexus center in Warsaw, you can consult with a psychiatrist who speaks both Polish and Russian and will help choose the treatment best suited to your needs and sensitivity. No judgment, no labels — just respect for your story and your pace. Recovery begins with connection. And that may be your first step toward meaningful change.