Viagra (sildenafil) is not FDA-approved for use in women, but it has been studied in clinical trials and is sometimes prescribed off-label. The safety profile in these studies has generally been favorable, with side effects similar to what men experience: headaches, flushing, and mild drops in blood pressure. However, the results for effectiveness are mixed, and the same serious drug interactions that apply to men apply to women too.
How Viagra Works in the Female Body
Viagra works by relaxing smooth muscle in blood vessels, increasing blood flow to the genitals. In men, this produces an erection. In women, the same mechanism increases blood flow to the clitoris and vaginal tissue, which can improve lubrication and genital sensation during arousal.
Reduced pelvic blood flow, particularly after menopause, can cause tissue changes in the clitoral area that lessen sexual sensation and make intercourse painful. In a study of postmenopausal women with orgasmic dysfunction, those taking sildenafil showed significantly improved clitoral blood flow compared to a placebo group after just 15 days of treatment. The improvement in blood flow correlated with better scores on a validated sexual function questionnaire.
What the Research Shows About Effectiveness
The largest controlled study, published in The Journal of Urology, tested sildenafil against a placebo in 202 postmenopausal women with arousal disorder over 12 weeks. The results were telling, but nuanced. For women whose primary issue was physical arousal (difficulty with lubrication, sensation, or orgasm), sildenafil worked significantly better than placebo on five out of six measures. Women taking the drug were about four times more likely to report improved vaginal lubrication and ability to reach orgasm, and roughly eleven times more likely to report an improved overall sexual experience compared to placebo.
But for women who also had low sexual desire, the drug didn’t outperform placebo on any measure. This makes sense given how Viagra works: it increases blood flow, but it doesn’t affect desire or arousal that originates in the brain. If the issue is wanting sex less rather than struggling with the physical response, Viagra is unlikely to help.
There’s also evidence supporting its use in a more specific situation. A randomized trial of 98 premenopausal women found sildenafil effective for sexual dysfunction caused by antidepressants, particularly the difficulty reaching orgasm that commonly accompanies SSRIs and similar medications. Since antidepressant-related sexual dysfunction is especially common in women, this represents a potentially meaningful use case.
Side Effects in Women
In clinical trials, women generally tolerated sildenafil well. A study of women with spinal cord injuries reported no significant adverse events. Cardiovascular monitoring showed modest increases in heart rate (around 5 beats per minute) and mild decreases in blood pressure (around 4 mmHg), both consistent with the drug’s blood vessel-relaxing effects. These changes were described as clinically insignificant.
The most commonly reported side effects in women mirror those in men: headache, facial flushing, nasal congestion, and visual disturbances. Most studies used a 50 mg dose, with some allowing adjustment up to 100 mg or down to 25 mg depending on response and tolerability.
The Serious Safety Concern
The one major danger with sildenafil applies equally to men and women: never combine it with nitrate medications. Nitrates are used for chest pain and heart conditions and include nitroglycerin patches, nitroglycerin tablets, and isosorbide. Both sildenafil and nitrates relax blood vessels, and combining them can cause a severe, potentially fatal drop in blood pressure.
Research published by the American Heart Association described how this combination can trigger a dangerous cycle in people with narrowed coronary arteries. The dramatic blood pressure drop reduces blood flow to the heart, which weakens the heart’s ability to pump, causing blood pressure to fall further. For anyone taking nitrates for a heart condition, sildenafil is not safe regardless of sex.
FDA-Approved Options for Women
While Viagra remains off-label for women, two medications have received FDA approval specifically for low sexual desire in premenopausal women. These work through entirely different mechanisms, targeting brain chemistry rather than blood flow.
- Flibanserin (Addyi) is a daily pill that acts on serotonin and dopamine pathways in the brain. It requires consistent daily use and cannot be combined with alcohol.
- Bremelanotide (Vyleesi) is an on-demand injection given under the skin of the abdomen or thigh at least 45 minutes before sexual activity. In clinical trials, 25% of women using it reported improved desire scores compared to 17% on placebo. It’s considered to have fewer side effects than flibanserin.
These drugs address desire, which is the piece Viagra can’t touch. For women whose difficulty is primarily physical arousal, lubrication, or reaching orgasm, neither of these approved options targets the same problem that sildenafil does, which partly explains why some doctors continue to prescribe it off-label despite the lack of FDA approval.
Who Might Benefit
Based on the available research, sildenafil is most likely to help women who experience physical arousal difficulties but still have intact sexual desire. This includes postmenopausal women dealing with reduced genital sensation or lubrication, and premenopausal women experiencing sexual side effects from antidepressants. For women whose primary concern is low desire, the evidence consistently shows sildenafil offers no meaningful benefit over placebo.
Because the drug isn’t approved for women, there are no standardized dosing guidelines. Studies have typically used 50 mg taken before sexual activity, with some participants using it several times per week. Any use in women would be at a prescriber’s discretion, and the decision should account for cardiovascular health, current medications, and whether the specific type of sexual difficulty is one that increased blood flow could realistically address.