When the Food and Drug Administration halted the use of Johnson & Johnson’s Covid-19 vaccine to assess the risk of blood clots in women under the age of 50 last month, many scientists noted that clots associated with birth control pills were far more common.

The comparison was meant to reassure women about the safety of the vaccine. Instead, it has infuriated some people, not because of the pause, but because the majority of contraceptives available to women are hundreds of times riskier, and safer alternatives are nowhere in sight. The clots linked to the vaccine were of a dangerous type in the brain, whereas birth control pills increase the chances of a blood clot in the leg or lung — a point that many experts quickly noted. However, for some women, the distinction made little difference.

Some women were told, on social media and elsewhere, that they should not complain because they chose to use birth control despite knowing the risks. “That just made me double down,” said Mia Brett, a legal historian specializing in race and sexuality. “This is such a common reaction to women’s health care — we point something out and it’s dismissed.”

Experts in women’s health were unsurprised by the outpouring of rage on the internet.  “They should be angry because women’s health simply does not receive equal attention,” said Dr. Eve Feinberg, a reproductive endocrinologist and infertility specialist at Northwestern University. “There is a significant sex bias in all of medicine.”

Dr. Feinberg and many of the women on the internet agree that contraception has given women control over their fertility, and the benefits outweigh the risks. Rebecca Fishbein, a 31-year-old culture writer, began tweeting about the inadequateness of birth control pills almost immediately after the pause was announced.

Contraception has also advanced over time, with intrauterine devices and oral contraceptives that provide an ultralow dose of estrogen. “Overall, it’s extremely safe,” said Dr. Feinberg. “Everything we do is fraught with danger.”

Dr. Feinberg, on the other hand, stressed the importance of health care providers discussing the risks with their patients and coaching them on concerning symptoms — a conversation that many women said they had never had.

Kelly Tyrrell, a communications professional from Madison, Wisconsin, was 37 years old when doctors discovered potentially fatal blood clots in her lungs.

Ms. Tyrrell is an endurance athlete — wiry, strong, and not easily frightened. She began waking up with pain in her left calf in early 2019. An urgent care visit after a particularly bad morning revealed that she had high blood levels of “D dimer,” a protein fragment that indicates the presence of clots.

She had been taking birth control pills for 25 years, but no doctor had noticed anything unusual. Instead, they stated that her symptoms were unlikely to be caused by a blood clot given her age, fitness, and lack of other risk factors. They sent her home with instructions to do calf muscle stretches.

Doctors said that when she felt a tightness in her chest while running in Hawaii after her grandmother’s funeral, it was most likely due to stress and anxiety. She finished a 100K race in Colorado in July 2019 and assumed her aching lungs and purple lips were the result of running for 19 hours at such a high altitude.

But she realized something was seriously wrong when she became short of breath after walking up a short flight of stairs on Oct. 24, 2019.

After ruling out any heart issues, doctors scanned her lungs and discovered multiple clots. One of them had cut off blood flow to part of her right lung.

Emily Farris, 36, was prescribed oral contraceptives for migraines when she was 18 years old. “Never once was blood clots brought up in any of the conversations I’ve had with my many doctors over the years,” she said in an interview. Some critics pointed out on Twitter that the inserts included with birth control packs clearly describe the risk of blood clots. Dr. Farris, a political scientist at Texas Christian University in Fort Worth, responded, “I’m a little skeptical of that.”

Most medication inserts include a lengthy list of potential side effects, putting “a high burden on folks to try to sort through medical research, to sort through what probability and statistics mean,” she said.