Can a partner actually feel a copper IUD or its strings during sex, and what factors affect whether it is noticeable?

Short answer

Yes, a partner can sometimes feel the IUD strings during sex [7][11][51]. But the IUD body itself normally cannot be felt: it is very small and sits inside the uterus, not in the vaginal canal, so it is outside the “penetration zone” [4][5][6][48][50]. If a partner feels the hard plastic device itself, that is not expected and could mean the IUD moved or was not placed correctly [4][10][50].

Feeling the strings usually should not hurt, because the strings are very thin plastic [7][16]. The chance that an IUD actually hurts a partner is low, and a string actually poking a partner’s penis is described as extremely rare [45][46].

What’s where

When an IUD is correctly placed, one or two thin plastic strings — usually about 2 inches long — hang down in the vaginal canal [32][47]. They sit high enough that they should not normally be felt, but feeling the threads is sometimes possible [6]. The strings are typically within fingertip reach when a person checks [33][47].

Factors that affect how noticeable the strings are

• Time. Many sources say the strings often soften, become more flexible, and curl or tuck around the cervix over time, which can make them less noticeable [8][44][49][52][53]. Some people find their strings “come and go” [3]. One Reddit commenter adds a different twist: the strings may not exactly soften, but they get covered in cervical mucus and become less irritating against the penis [41].
• Cervical mucus. Mucus can cover or mask the strings, which can make them less noticeable during sex [41][42].
• Position and body factors. The strings can curl or coil near the cervix [27][31][36], hide in a fold of vaginal tissue [28][38], be cut too short, or be too far inside the vagina to reach [29][34][35]. If the IUD rotates, the strings can move out of reach; they may return to their normal position by the next menstrual cycle [37][39].
• Type of sex. A partner with a penis probably will not feel the strings intensely, but the strings are easier to notice during fingering [43].
• Practical fixes. Using condoms, curling the strings closer to the cervix, or having a clinician trim or curl the strings can make them less noticeable [1][2][12][44][52]. Trimming has tradeoffs: very short strings may stop being felt, but they can stick out straight and make removal harder or more complicated [9][14][18].
• Study findings. One study found that string length, days since insertion, IUD type, and BMI did not affect women’s ability to feel the strings at the study visit, and all 126 participants had visible strings [20][21]. In another study of postplacental insertion, the strings were not visible in 21% of IUDs still in the uterus; at one year, visibility was lower after intra-caesarean insertion than after vaginal insertion, and ultrasound confirmed the IUDs were still in the uterus [22][23][24].

When to check with a clinician

If either partner feels the IUD itself or hard plastic, contact a clinician [4]. That may mean the IUD moved or was not placed properly [10]. Perforation of the cervix or uterus is one complication that can cause pelvic pain, bleeding, and pain during sex [30].