Common symptoms of stress include: A fast heartbeat.A headache.A stiff neck and/or tight shoulders. Back pain. Fast breathing. Sweating, and sweaty palms. An upset stomach, nausea, or diarrhea. Over time, stress can affect your:1 Immune system. Constant stress can make you more likely to get sick more often. And if you have a chronic illness such as AIDS, stress can make your symptoms worse. Heart. Stress is linked to high blood pressure, abnormal heartbeat (arrhythmia), blood clots, and hardening of the arteries (atherosclerosis). It's also linked to coronary artery disease, heart attack, and heart failure.