Shivering After Tadalafil: Not a Typical Side Effect
The shivering you describe 2-3 hours after taking tadalafil is not a recognized or expected side effect of this medication, and you should contact your healthcare provider to evaluate for other causes, particularly infection or other medical conditions.
Understanding Tadalafil's Known Side Effects
The FDA-approved drug label for tadalafil (Cialis) lists the most common side effects as 1:
- Headache
- Indigestion
- Back pain
- Muscle aches
- Flushing
- Stuffy or runny nose
Shivering or chills are not listed among the known adverse effects of tadalafil in either the FDA labeling 1 or in major clinical trials involving thousands of patients 2, 3, 4.
Your Blood Pressure Reading
Your blood pressure of 155/84 mmHg is mildly elevated but not dangerously high. Importantly:
- Tadalafil typically causes small decreases in blood pressure, not increases 5
- In healthy subjects and patients with cardiovascular disease, tadalafil resulted in small blood pressure reductions that are not clinically significant 5
- The fact that your thigh muscle pain resolved is reassuring, as muscle aches are a known side effect that typically resolve within 2 days 1
What You Should Do
Contact your healthcare provider promptly because shivering (especially when it feels like fever chills) suggests:
- Possible infection or illness - This is the most common cause of shivering and should be ruled out
- Other medical conditions unrelated to tadalafil
- Coincidental timing - The shivering may have started around the time you took tadalafil but not be caused by it
Important Safety Considerations
While your symptoms are unlikely related to tadalafil, be aware of serious side effects that DO require immediate medical attention 1:
- Erection lasting more than 4 hours (priapism)
- Sudden vision loss or changes
- Sudden hearing loss (sometimes with ringing in ears and dizziness)
- Chest pain, dizziness, or nausea during sexual activity
The Bottom Line
Tadalafil has been extensively studied in over 4,000 subjects with a well-established safety profile 5. The most frequent adverse events are vasodilation-related (headache, flushing, dyspepsia) and musculoskeletal (back pain, myalgia) 2. Shivering is not part of this profile and warrants medical evaluation for alternative causes. Your resolved muscle pain and mildly elevated blood pressure are not concerning for tadalafil toxicity, but the new onset of shivering needs proper assessment.