Symptom Frequency
| Symptom | P | Caffeine consumers | Non–caffeine consumers |
| All symptoms | 0.9579 | ||
| Aminophylline use | 0.0371 | 18% | 45% |
| Palpitations | 0.2053 | 2% | 9% |
| Shortness of breath | 0.4972 | 23% | 30% |
| Flushing | 0.9241 | 10% | 9% |
| Chest pain | 0.0013 | 10% | 45% |
| Headache | 0.2713 | 14% | 27% |
| Nausea or vomiting | 0.8218 | 16% | 18% |
| Dizziness | 0.1018 | 20% | 0% |
| Feeling hot | 0.5387 | 3% | 0% |
| Abdominal pain | 0.2718 | 10% | 0% |
| Back pain | 0.7253 | 1% | 0% |
| Dysgeusia | 0.2053 | 2% | 9% |