You can get side effects from using Viagra, and some men taking certain medications or with medical conditions shouldn’t use it.
If you experience:
- chest pain
- sight loss
- an erection that lasts for four or more hours and won’t go away
- an allergic reaction
- any skin reaction such as blistering
- or any other side effects that concern you;
speak to a doctor right away.
Very common (more than 1 in 10 users):
Headache.
Common (less than 1 in 10 users):
Feeling sick, flushing in the face, hot flush, indigestion problems, color tinted vision, sight problems like blurred vision or visual disturbance, blocked or stuffy nose and feeling dizzy.
Uncommon (less than 1 in 100 users):
Being sick, rash, eye irritation, bloodshot or red eyes, eye pain, seeing flashes of light, visual brightness, being sensitive to light, watery eyes, palpitations, fast heartbeat, high blood pressure, low blood pressure, pain in the muscles, drowsiness, loss of sense of touch, vertigo, ringing in the ears, mouth feeling more dry than usual, blocked or stuffy sinuses, inflammation of the lining of the nose, causing runny nose, sneezing and blocked nose, pain above the stomach, gastro-oesophageal reflux disease causing heartburn, blood in the urine, arm or leg pain, bleeding from the nose, feeling hot and tired.
Rare (less than 1 in 1,000 people):
Fainting, stroke, heart attack, irregular heartbeat, temporary reduced blood flow to sections of the brain, throat becoming tight, numb mouth, bleeding behind the eye, double vision, loss of visual sharpness, unusual feeling in the eye, swollen eye or eyelid, small particles or floaters in your vision, seeing bright round circles around lights, dilated pupils, change of color in the white of the eye, bleeding from the penis, blood in the semen, dry nose, nasal inflammation, feeling irritable and sudden loss of hearing.