Cialis (tadalafil) is taken as an oral tablet, either once daily at a low dose or as needed before sexual activity. You can take it with or without food, and it reaches peak levels in your bloodstream about two hours after swallowing, though the window ranges from 30 minutes to six hours.
Two Ways to Take It
Cialis is prescribed in one of two regimens, and how you take it depends on which one your provider chose for you.
The as-needed approach means you take a tablet before anticipated sexual activity. Most men take it roughly 30 minutes to two hours beforehand, but because it stays active far longer than similar medications (its half-life is about 17.5 hours), you have a wide window. A single dose can remain effective for up to 36 hours, which is why Cialis earned the nickname “the weekend pill.”
The daily approach uses a lower dose taken at the same time every day, regardless of when you plan to have sex. This keeps a steady level of the drug in your system so you don’t need to plan around timing. If you miss a dose, take it when you remember, but skip it if your next scheduled dose is coming up soon. Never double up.
How to Swallow the Tablet
Standard tablets should be swallowed whole with water. Do not split, crush, or chew them. If you’ve been prescribed the chewable form, chew it completely before swallowing rather than swallowing it whole. That’s the one exception.
Food does not affect how the drug works. Unlike some other erectile dysfunction medications that absorb more slowly after a heavy meal, Cialis can be taken on a full or empty stomach without changing its effectiveness.
Alcohol and Cialis
Both Cialis and alcohol lower blood pressure. Combining them can cause dizziness, lightheadedness, or fainting. If you drink while taking Cialis, keep it to no more than four drinks in a short period. Less is better. The risk increases with heavier drinking because the blood pressure drop becomes more pronounced.
Why You Should Avoid Grapefruit
Grapefruit contains natural compounds that block an enzyme your body uses to break down Cialis before it enters the bloodstream. When that enzyme is suppressed, more of the drug gets through, and blood levels rise. In animal studies, grapefruit juice increased peak blood concentrations of tadalafil by 75%. That’s enough to amplify side effects like headaches, flushing, dizziness, and indigestion.
A single eight-ounce glass of grapefruit juice can suppress this enzyme for 24 to 72 hours. If you take Cialis daily, the safest choice is to avoid grapefruit entirely. For as-needed use, providers typically suggest waiting at least 72 hours after consuming grapefruit before taking a dose. The same applies to pomelo juice and Seville (bitter) orange juice, which is commonly found in orange marmalade.
Medications You Cannot Combine With Cialis
Cialis is strictly contraindicated with nitrate medications, which are commonly prescribed for chest pain and heart conditions. Nitroglycerin tablets, patches, and sprays all fall into this category. Both nitrates and Cialis lower blood pressure through related pathways, and combining them can cause a dangerous, potentially life-threatening drop in blood pressure. This applies whether you take nitrates daily or only occasionally. There is no safe timing window that makes the combination acceptable.
Common Side Effects
Most side effects are mild and tend to decrease with continued use. In long-term safety data, the most frequently reported were headache (about 16% of users), indigestion (12%), nasal congestion or a runny nose (11%), and back pain (8%). Back pain and muscle aches are somewhat unique to Cialis compared to other erectile dysfunction drugs and typically appear 12 to 24 hours after a dose, resolving on their own within a couple of days.
If you experience sudden vision or hearing changes, or an erection lasting longer than four hours, those require immediate medical attention. These are rare but serious.
Storing Your Medication
Keep Cialis at room temperature, ideally between 68°F and 77°F. Brief exposure to temperatures as low as 59°F or as high as 86°F is fine, such as during travel. Store it in a cool, dry place away from bathroom humidity, and keep it in its original packaging until you’re ready to take a dose.