When taken as PrEP, Truvada is not associated with clinically significant bone density loss in adults. Let's unpack what that means:

• Is there evidence of bone density loss in people taking Truvada as PrEP? Yes, a small decrease in bone mineral density (0.5-1.5%) has been seen in the first 6 months after starting PrEP. In studies, there has been no increase in bone fractures.
• Bone mineral density does not continue to decrease after the first six months, and it returns to normal within 6-12 months after discontinuing PrEP.

Note: We say the BMD loss is statistically significant because we can measure it consistently in people on PrEP and know that is associated with PrEP and is not a matter of chance. We say the BMD loss is not clinically significant because it does not lead to bad outcomes such an increase in fractures or other bone injuries.

Individuals can weigh the slight loss of bone density associated with PrEP against the risk of acquiring HIV. For people on lifelong treatment for HIV, there is strong evidence of clinically significant bone density loss. The researchers who studied BMD loss in PrEP users concluded: "The relatively small bone loss associated with FTC/TDF [Truvada] PrEP is offset by the prevention of HIV infection, which requires combination ART that is associated with relatively greater loss of BMD."

Bone mineral density can be measured using a test called a bone density scan. Some healthcare providers recommend a bone density scan before starting PrEP for people with or at high risk for osteoporosis. For people with normal bone health, this test is usually not recommended. Bone density scans are not recommended in the Clinical Practice Guideline (US Centers for Disease Control).